diff --git a/core/model/SiteTree.php b/core/model/SiteTree.php
index 65f1220eb..3eb4dfd82 100644
--- a/core/model/SiteTree.php
+++ b/core/model/SiteTree.php
@@ -78,8 +78,6 @@ class SiteTree extends DataObject {
 		"HasBrokenLink" => "Boolean",
 		"Status" => "Varchar",
 		"ReportClass" => "Varchar",
-		"Priority" => "Float",
-
 		"CanViewType" => "Enum('Anyone, LoggedInUsers, OnlyTheseUsers, Inherit', 'Inherit')",
 		"CanEditType" => "Enum('LoggedInUsers, OnlyTheseUsers, Inherit', 'Inherit')",
 
@@ -87,10 +85,10 @@ class SiteTree extends DataObject {
 		"ToDo" => "Text",
 	);
 
-  static $indexes = array(
-    "SearchFields" => "fulltext (Title, MenuTitle, Content, MetaTitle, MetaDescription, MetaKeywords)",
-    "TitleSearchFields" => "fulltext (Title)",
-	"URLSegment" => true,
+	static $indexes = array(
+		"SearchFields" => "fulltext (Title, MenuTitle, Content, MetaTitle, MetaDescription, MetaKeywords)",
+		"TitleSearchFields" => "fulltext (Title)",
+		"URLSegment" => true,
 	);
 
 	static $has_many = array(
@@ -555,7 +553,7 @@ class SiteTree extends DataObject {
 	 * - canEdit() is not granted
 	 * - There are no classes defined in {@link $allowed_children}
 	 * 
-	 * @uses DataObjectDecorator->canAddChildren()
+	 * @uses SiteTreeDecorator->canAddChildren()
 	 * @uses canEdit()
 	 * @uses $allowed_children
 	 *
@@ -644,6 +642,7 @@ class SiteTree extends DataObject {
 	 * - any descendant page returns FALSE for canDelete()
 	 * 
 	 * @uses canDelete()
+	 * @uses DataObjectDecorator->canDelete()
 	 * @uses canEdit()
 	 *
 	 * @param Member $member
@@ -686,6 +685,7 @@ class SiteTree extends DataObject {
 	 * Use {@link canAddChildren()} to control behaviour of creating children under this page.
 	 * 
 	 * @uses $can_create
+	 * @uses DataObjectDecorator->canCreate()
 	 *
 	 * @param Member $member
 	 * @return boolean True if the current user can create pages on this class.
@@ -721,6 +721,7 @@ class SiteTree extends DataObject {
 	 * 
 	 * @uses canView()
 	 * @uses EditorGroups()
+	 * @uses DataObjectDecorator->canEdit()
 	 *
 	 * @param Member $member
 	 * @return boolean True if the current user can edit this page.
@@ -768,7 +769,7 @@ class SiteTree extends DataObject {
 	 * - canPublish() on any decorator returns FALSE
 	 * - canEdit() returns FALSE
 	 * 
-	 * @uses DataObjectDecorator->canPublish()
+	 * @uses SiteTreeDecorator->canPublish()
 	 *
 	 * @param Member $member
 	 * @return boolean True if the current user can publish this page.
@@ -988,12 +989,6 @@ class SiteTree extends DataObject {
 			}
 		}
 
-
-		// If priority is empty or invalid, set it to the default value
-		if(!is_numeric($this->Priority) ||
-			 (($this->Priority < 0) || ($this->Priority > 1)))
-			$this->Priority = self::$defaults['Priority'];
-
 		parent::onBeforeWrite();
 	}
 	
@@ -1045,22 +1040,6 @@ class SiteTree extends DataObject {
 		}
 	}
 
-	/**
-	 * The default value of the priority field depends on the depth of the page in
-	 * the site tree, so it must be calculated dynamically.
-	 */
-	function getPriority() {		
-		if(!$this->getField('Priority')) {
-			$parentStack = $this->parentStack();
-			$numParents = is_array($parentStack) ? count($parentStack) - 1: 0;
-			return max(0.1, 1.0 - ($numParents / 10));
-		} else if($this->getField('Priority') == -1) {
-			return 0;
-		} else {
-			return $this->getField('Priority');
-		}
-	}
-
 	/**
 	 * Returns a FieldSet with which to create the CMS editing form.
 	 *
@@ -1137,22 +1116,6 @@ class SiteTree extends DataObject {
 		if(isset($statusMessage)) {
 			$message .= "NOTE: " . implode("<br />", $statusMessage);
 		}
-
-
-		$pagePriorities = array(
-			'' => _t('SiteTree.PRIORITYAUTOSET','Auto-set based on page depth'),
-			'-1' => _t('SiteTree.PRIORITYNOTINDEXED', "Not indexed"), // We set this to -ve one because a blank value implies auto-generation of Priority
-			'1.0' => '1 - ' . _t('SiteTree.PRIORITYMOSTIMPORTANT', "Most important"),
-			'0.9' => '2',
-			'0.8' => '3',
-			'0.7' => '4',
-			'0.6' => '5',
-			'0.5' => '6',
-			'0.4' => '7',
-			'0.3' => '8',
-			'0.2' => '9',
-			'0.1' => '10 - ' . _t('SiteTree.PRIORITYLEASTIMPORTANT', "Least important")
-		);
 		
 		// Lay out the fields
 		$fields = new FieldSet(
@@ -1190,27 +1153,7 @@ class SiteTree extends DataObject {
 						new TextField("MetaTitle", $this->fieldLabel('MetaTitle')),
 						new TextareaField("MetaDescription", $this->fieldLabel('MetaDescription')),
 						new TextareaField("MetaKeywords", $this->fieldLabel('MetaKeywords')),
-						new ToggleCompositeField(
-							'AdvancedOptions',
-							_t('SiteTree.METAADVANCEDHEADER', "Advanced Options..."),
-							array( 
-								new TextareaField("ExtraMeta",$this->fieldLabel('ExtraMeta')), 
-								new LiteralField(
-									"", 
-									"<p>" .
-									sprintf(
-										_t(
-											'SiteTree.METANOTEPRIORITY', 
-											"Manually specify a Google Sitemaps priority for this page (%s)"
-										),
-										'<a href="https://www.google.com/webmasters/tools/docs/en/protocol.html#prioritydef">?</a>'
-									) .
-									"</p>"
-								), 
-								new DropdownField("Priority", $this->fieldLabel('Priority'), $pagePriorities)
-							), 
- 							true 
-						)
+						new TextareaField("ExtraMeta",$this->fieldLabel('ExtraMeta'))
 					)
 				),
 				$tabBehaviour = new Tab('Behaviour',
@@ -1301,7 +1244,6 @@ class SiteTree extends DataObject {
 		$labels['MetaDescription'] = _t('SiteTree.METADESC', "Description");
 		$labels['MetaKeywords'] = _t('SiteTree.METAKEYWORDS', "Keywords");
 		$labels['ExtraMeta'] = _t('SiteTree.METAEXTRA', "Custom Meta Tags");
-		$labels['Priority'] = _t('SiteTree.METAPAGEPRIO', "Page Priority");
 		$labels['ClassName'] = _t('SiteTree.PAGETYPE', "Page type", PR_MEDIUM, 'Classname of a page object');
 		$labels['ShowInMenus'] =_t('SiteTree.SHOWINMENUS', "Show in menus?");
 		$labels['ShowInSearch'] = _t('SiteTree.SHOWINSEARCH', "Show in search?");
@@ -1360,7 +1302,10 @@ class SiteTree extends DataObject {
 	}
 	
 	/**
-	 * Publish this page
+	 * Publish this page.
+	 * 
+	 * @uses SiteTreeDecorator->onBeforePublish()
+	 * @uses SiteTreeDecorator->onAfterPublish()
 	 */
 	function doPublish() {
 		$original = Versioned::get_one_by_stage("SiteTree", "Live", "\"SiteTree\".\"ID\" = $this->ID");
@@ -1373,8 +1318,6 @@ class SiteTree extends DataObject {
 		//$this->PublishedByID = Member::currentUser()->ID;
 		$this->write();
 		$this->publish("Stage", "Live");
-		
-		GoogleSitemap::ping();
 
 		if(DB::getConn() instanceof MySQLDatabase) {
 			// Special syntax for MySQL (grr!)
@@ -1399,8 +1342,13 @@ class SiteTree extends DataObject {
 	
 	/**
 	 * Unpublish this page - remove it from the live site
+	 * 
+	 * @uses SiteTreeDecorator->onBeforeUnpublish()
+	 * @uses SiteTreeDecorator->onAfterUnpublish()
 	 */
 	function doUnpublish() {
+		$this->extend('onBeforeUnpublish');
+		
 		// Call delete on a cloned object so that this one doesn't lose its ID
 		$this->flushCache();
 		$clone = DataObject::get_by_id("SiteTree", $this->ID);
@@ -1408,8 +1356,8 @@ class SiteTree extends DataObject {
 
 		$this->Status = "Unpublished";
 		$this->write();
-
-		GoogleSitemap::ping();
+		
+		$this->extend('onAfterUnpublish');
 	}
 	
 	/**
diff --git a/integration/GoogleSitemap.php b/integration/GoogleSitemap.php
index 3230905b5..3d4b6cc0f 100755
--- a/integration/GoogleSitemap.php
+++ b/integration/GoogleSitemap.php
@@ -1,9 +1,21 @@
 <?php
-
 /**
  * Initial implementation of Sitemap support.
  * GoogleSitemap should handle requests to 'sitemap.xml'
- * the other two classes are used to render the sitemap
+ * the other two classes are used to render the sitemap.
+ * 
+ * You can notify ("ping") Google about a changed sitemap
+ * automatically whenever a new page is published or unpublished.
+ * By default, Google is not notified, and will pick up your new
+ * sitemap whenever the GoogleBot visits your website.
+ * 
+ * Enabling notification of Google after every publish (in your _config.php):
+ * <example
+ * GoogleSitemap::enable_google_notificaton();
+ * </example>
+ * 
+ * @see http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=34609
+ * 
  * @package sapphire
  * @subpackage misc
  */
@@ -22,7 +34,7 @@ class GoogleSitemap extends Controller {
 	/**
 	 * @var boolean
 	 */
-	protected static $pings = true;
+	protected static $google_notification_enabled = false;
 	
 	public function Items() {
 		$this->Pages = Versioned::get_by_stage('SiteTree', 'Live');
@@ -70,13 +82,21 @@ class GoogleSitemap extends Controller {
 	}
 	
 	/**
+	 * Notifies Google about changes to your sitemap.
+	 * Triggered automatically on every publish/unpublish of a page.
+	 * This behaviour is disabled by default, enable with:
+	 * GoogleSitemap::enable_google_notificaton();
+	 * 
+	 * If the site is in "dev-mode", no ping will be sent regardless wether
+	 * the Google notification is enabled.
+	 * 
 	 * @return string Response text
 	 */
 	static function ping() {
 		if(!self::$enabled) return false;
 		
 		//Don't ping if the site has disabled it, or if the site is in dev mode
-		if(!GoogleSitemap::$pings || Director::isDev())
+		if(!GoogleSitemap::$google_notification_enabled || Director::isDev())
 			return;
 			
 		$location = urlencode(Director::absoluteBaseURL() . '/sitemap.xml');
@@ -87,15 +107,18 @@ class GoogleSitemap extends Controller {
 		return $response;
 	}
 	
+	/**
+	 * Enable pings to google.com whenever sitemap changes.
+	 */
 	public static function enable_google_notification() {
-		self::$pings = true;
+		self::$google_notification_enabled = true;
 	}
 	
 	/**
 	 * Disables pings to google when the sitemap changes.
 	 */
 	public static function disable_google_notification() {
-		self::$pings = false;
+		self::$google_notification_enabled = false;
 	}
 	
 	function index($url) {
@@ -120,4 +143,89 @@ class GoogleSitemap extends Controller {
 		self::$enabled = false;
 	}
 }
-?>
+
+/**
+ * @package sapphire
+ * @subpackage misc
+ */
+class GoogleSitemapDecorator extends SiteTreeDecorator {
+	
+	function extraStatics() {
+		return array(
+			'db' => array(
+				"Priority" => "Float",
+			)
+		);
+	}
+	
+	function updateCMSFields(&$fields) {
+		$pagePriorities = array(
+			'' => _t('SiteTree.PRIORITYAUTOSET','Auto-set based on page depth'),
+			'-1' => _t('SiteTree.PRIORITYNOTINDEXED', "Not indexed"), // We set this to -ve one because a blank value implies auto-generation of Priority
+			'1.0' => '1 - ' . _t('SiteTree.PRIORITYMOSTIMPORTANT', "Most important"),
+			'0.9' => '2',
+			'0.8' => '3',
+			'0.7' => '4',
+			'0.6' => '5',
+			'0.5' => '6',
+			'0.4' => '7',
+			'0.3' => '8',
+			'0.2' => '9',
+			'0.1' => '10 - ' . _t('SiteTree.PRIORITYLEASTIMPORTANT', "Least important")
+		);
+		
+		$tabset = $fields->findOrMakeTab('Root.Content');
+		$tabset->push(
+			$addTab = new Tab(
+				'GoogleSitemap',
+				_t('SiteTree.TABGOOGLESITEMAP', 'Google Sitemap'),
+				new LiteralField(
+					"GoogleSitemapIntro", 
+					"<p>" .
+					sprintf(
+						_t(
+							'SiteTree.METANOTEPRIORITY', 
+							"Manually specify a Google Sitemaps priority for this page (%s)"
+						),
+						'<a href="https://www.google.com/webmasters/tools/docs/en/protocol.html#prioritydef">?</a>'
+					) .
+					"</p>"
+				), 
+				new DropdownField("Priority", $this->owner->fieldLabel('Priority'), $pagePriorities)
+			)
+		);
+	}
+	
+	function updateFieldLabels(&$labels) {
+		parent::updateFieldLabels($labels);
+		
+		$labels['Priority'] = _t('SiteTree.METAPAGEPRIO', "Page Priority");
+	}
+	
+	function onAfterPublish() {
+		GoogleSiteMap::ping();
+	}
+	
+	function onAfterUnpublish() {
+		GoogleSiteMap::ping();
+	}
+	
+	/**
+	 * The default value of the priority field depends on the depth of the page in
+	 * the site tree, so it must be calculated dynamically.
+	 */
+	function getPriority() {		
+		if(!$this->owner->getField('Priority')) {
+			$parentStack = $this->owner->parentStack();
+			$numParents = is_array($parentStack) ? count($parentStack) - 1: 0;
+			return max(0.1, 1.0 - ($numParents / 10));
+		} else if($this->owner->getField('Priority') == -1) {
+			return 0;
+		} else {
+			return $this->owner->getField('Priority');
+		}
+	}
+}
+
+Object::add_extension('SiteTree', 'GoogleSitemapDecorator');
+?>
\ No newline at end of file