Just an idea for implementing it quickly.

You can take existing code and bolt this code on, and then use it to produce somewhat readable code with rudimentary security features.

// $GROUPS = array( 'Guest', 'Unconfirmed', 'Approval', 'Active', 'Rejected', 'Admin', 'Moderator' ); 

$ACCESS = array(
	'view_friends' => array( 'group', 'group2', 'group3' ),
	'view_comments' => array( 'group', 'group2', 'group3' ),
	'suspend_user' => array( 'group', 'group2', 'group3' ),
	'use_chatroom' => array( 'group', 'group2', 'group3' ),
	'send_message_as_mail' => array( 'group', 'group2', 'group3' ),
	'ability' => array( 'group', 'group2', 'group3' )
);

function cando( $user, $ability )
{
	// get the user's groups
	// check permissions for an ability
	// return true if their groups are in the ability's array
}