Assuming I have a valid session and an authenticated user, what are some ways to go about implementing user authorization in an application with a PHP/MySQL backend, and a h
It seems that you are looking for something called Access Control List aka ACL (which is dead according to Zed Shaw, great video).
It's pretty hard to give a you a solution without knowing what kind of backend you have, but you might check out how other are doing that.
For something specific to the lithium framework (PHP), see: Lithium Access Control