public static function getTS($value = null)
	{
		if ($value === null)
		{
			return sfDateTimeToolkit::now();
		}
		else if ($value instanceof sfDate)
		{
			return $value->get();
		}
		else if (!is_numeric($value))
		{
			return strtotime($value);
		}
		else if (is_numeric($value))
		{
			return $value;
		}
		
		throw new sfDateTimeException(sprintf('A timestamp could not be retrieved from the value: %s', $value));
	}