public function save(Application_Model_Comment $comment)
 {
     $data = array('password' => $comment->getPassword(), 'username' => $comment->getUserName());
     if (null === ($id = $comment->getId())) {
         unset($data['id']);
         $this->getDbTable()->insert($data);
     } else {
         $this->getDbTable()->update($data, array('id = ?' => $id));
     }
 }