public function updateLoginStats($userId, $columns = array()) {
        if (isset($_SERVER['REMOTE_ADDR'])) {
            $columns['ip_address'] = $_SERVER['REMOTE_ADDR'];
        }
        $columns['last_login'] = new Zend_Db_Expr('NOW()');
        return $this->_model->update(
            $columns,
            $this->_model->getAdapter()->quoteInto('user_id = ?', $userId)
        );
    }