Access Control is an interesting idea. Personally, I'd rather see be able to access hidden applications with gestures on the desktop instead of having to go into Settings ==> Access Control ... but anyway, it's a nice feature. However it has a serious flaw. If someone has accessed a hidden application recently, another user can hold down the Home button to access the task manager, and select 'Settings'. This will go directly to the list of hidden applications, allowing someone to start one without entering a password / whatever.