Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 12155)
+++ wp-includes/post.php	(working copy)
@@ -694,7 +694,7 @@
 	if ( $post_ids ) {
 		$postmetaids = $wpdb->get_col( $wpdb->prepare( "SELECT meta_id FROM $wpdb->postmeta WHERE meta_key = %s", $post_meta_key ) );
 		do_action( 'delete_postmeta', $postmetaids );
-		$wpdb->query( $wpdb->prepare("DELETE FROM $wpdb->postmeta WHERE meta_id IN(%s)", implode( ',', $postmetaids) ) );
+		$wpdb->query( "DELETE FROM $wpdb->postmeta WHERE meta_id IN(" . implode( ',', $postmetaids) . ')' );
 		do_action( 'deleted_postmeta', $postmetaids );
 		foreach ( $post_ids as $post_id )
 			wp_cache_delete($post_id, 'post_meta');