I was having some problems trying to use the beforeFilter function in my controllers because I was using it in app_controller.php as well. In app_controller.php I was playing with the session variables and this was breaking when I went to use the beforeFilter function in any of my controllers. The workaround is very simple and came from the mailing list.
In you controller version of the beforeFilter function, add in the following line:
parent::beforeFilter();
before you do anything in the function. This explicitly calls the beforeFilter function in app_controller.php and runs it first.
Thanks to Jon Bennet for that little nugget


