Index: includes/parser/Parser.php
===================================================================
--- includes/parser/Parser.php	(revision 46189)
+++ includes/parser/Parser.php	(working copy)
@@ -3439,6 +3439,9 @@
 				wfDebug( __METHOD__.": [[MediaWiki:hidden-category-category]] is not a valid title!\n" );
 			}
 		}
+		if ( isset( $this->mDoubleUnderscores['ignoreunused'] ) && $this->mTitle->getNamespace() == NS_CATEGORY ) {
+			$this->mOutput->setProperty( 'ignoreunused', 'y' );
+		}
 		# (bug 8068) Allow control over whether robots index a page.
 		#
 		# FIXME (bug 14899): __INDEX__ always overrides __NOINDEX__ here!  This
Index: includes/MagicWord.php
===================================================================
--- includes/MagicWord.php	(revision 46189)
+++ includes/MagicWord.php	(working copy)
@@ -159,6 +159,7 @@
 		'noeditsection',
 		'newsectionlink',
 		'hiddencat',
+		'ignoreunused',
 		'index',
 		'noindex',
 		'staticredirect',
Index: includes/specials/SpecialUnusedcategories.php
===================================================================
--- includes/specials/SpecialUnusedcategories.php	(revision 46189)
+++ includes/specials/SpecialUnusedcategories.php	(working copy)
@@ -22,14 +22,16 @@
 	function getSQL() {
 		$NScat = NS_CATEGORY;
 		$dbr = wfGetDB( DB_SLAVE );
-		list( $categorylinks, $page ) = $dbr->tableNamesN( 'categorylinks', 'page' );
+		list( $categorylinks, $page, $page_props ) = $dbr->tableNamesN( 'categorylinks', 'page', 'page_props' );
 		return "SELECT 'Unusedcategories' as type,
 				{$NScat} as namespace, page_title as title, page_title as value
 				FROM $page
 				LEFT JOIN $categorylinks ON page_title=cl_to
+				LEFT JOIN $page_props ON pp_page=page_id
 				WHERE cl_from IS NULL
 				AND page_namespace = {$NScat}
-				AND page_is_redirect = 0";
+				AND page_is_redirect = 0
+				AND (pp_propname IS NULL OR pp_propname != 'ignoreunused')";
 	}
 
 	function formatResult( $skin, $result ) {
Index: languages/messages/MessagesEn.php
===================================================================
--- languages/messages/MessagesEn.php	(revision 46189)
+++ languages/messages/MessagesEn.php	(working copy)
@@ -327,6 +327,7 @@
 	'filepath'               => array( 0,    'FILEPATH:'              ),
 	'tag'                    => array( 0,    'tag'                    ),
 	'hiddencat'              => array( 1,    '__HIDDENCAT__'          ),
+	'ignoreunused'           => array( 1,    '__IGNOREUNUSED__'       ),
 	'pagesincategory'        => array( 1,    'PAGESINCATEGORY', 'PAGESINCAT' ),
 	'pagesize'               => array( 1,    'PAGESIZE'               ),
 	'index'                  => array( 1,    '__INDEX__'              ),