public function RecentEvents($limit = null, $filter = null, $announcement_filter = null)
 {
     $start_date = new sfDate();
     $end_date = new sfDate();
     $events = $this->Events($filter, $start_date->subtractMonth(Calendar::$defaultFutureMonths), $end_date->yesterday(), true, $limit === null ? $this->DefaultEventDisplay : $limit, $announcement_filter);
     $events->sort('StartDate', 'DESC');
     return $events;
 }