Fuel PHP is a 5.3 framework

Exception.php

<?php
/**
 * Fuel
 *
 * Fuel is a fast, lightweight, community driven PHP5 framework.
 *
 * @package    Fuel
 * @version    1.0
 * @author     Fuel Development Team
 * @license    MIT License
 * @copyright  2010 - 2011 Fuel Development Team
 * @link       http://fuelphp.com
 */

namespace Fuel\Core\Cache;

class Exception extends \Fuel\Core\Exception {}

/* 
 * Current implementation
 * 
 * namespace Fuel\Core;
 * class Cache_Exception extends Fuel_Exception {}
 * 
 * Is there any advantage of this way? We already have namespace now in PHP 5.3 and are using it .
 * though I think it meets http://groups.google.com/group/php-standards/web/psr-0-final-proposal?pli=1
 * One more doubt is can we utilise other third party libraries inside fuel?
 * Sorry if I was lazy not finding the right explanation, I would be greatful if you point me there :).
 * Thanks
**/