if ( !empty($q['meta_key']) ) {
              $allowed_keys[] = $q['meta_key'];
              $allowed_keys[] = 'meta_value';
+             $allowed_keys[] = 'meta_value_num';
      }
      $q['orderby'] = urldecode($q['orderby']);
      $q['orderby'] = addslashes_gpc($q['orderby']);

     case 'meta_value':
              $orderby = "$wpdb->postmeta.meta_value";
              break;
+     case 'meta_value_num':
+             $orderby = "$wpdb->postmeta.meta_value+0";
+             break;
      default:
              $orderby = "$wpdb->posts.post_" . $orderby;
}