I've been reading up on how to access Joomla from external php scripts and I've noticed that there tends to be 2 flavours of code- external scripts that use require('libraries/joomla/factory.php');
and those that don't.
factory.php doesn't seem to be necessary, so for what reason(s) would you include it?
EDIT Here is an example of code that uses factory.php
define('_JEXEC', 1);
define('JPATH_BASE', realpath(dirname(__FILE__)));
require_once ( JPATH_BASE .'/includes/defines.php' );
require_once ( JPATH_BASE .'/includes/framework.php' );
require_once ( JPATH_BASE .'/libraries/joomla/factory.php' );