A new feature that will be in the coming release candidate 4 is the function referer() in the controller. Well, that feature is not worldshaking, it is simply a convenience function to get the referer. You can use it in your controller as you would expect:
$this->referer();
Thank for the good news! How did you become aware of it?
Anyway, check out my last comment to the ticket:
https://trac.cakephp.org/ticket/314
I use the trunk version of CakePHP, and so I see the changes made to the code.