Mine

<?php
class Auth
{
	public $sessiondata = array();

	function Auth()
	{
		$this->object =& get_instance();
		$this->object->load->library('session');

		log_message('debug', "Auth Class Initialized");

		$this->load_session();
	}

	function create_session( $username, $password )
	{
		
	}

	function load_session()
	{
		if ( $this->object->session->userdata('user_id') )
		{
			// Make sure session is valid here ..

			$this->sessiondata['session_logged_in'] = true;
		}
		else
		{
			$this->sessiondata['session_logged_in'] = false;
		}
	}

	function destroy_session()
	{
		return ( $this->session->sess_destroy() ) ? true : false;
	}
}
?>