HttpSession Wrapper Class
There are a few things I see:


Work in the constructor - Don't do work in the constructor. Ideally the only things that should be in the constructor are assignments.
DRY - Why are you repeating $this-&gt;start() all over the place?
What's up with that destroy() method? You're doing stuff there other than destroying the session! Why?
Your session_start() should happen once, in the constructor.
It would be more flexible if you passed the $_SESSION array as a parameter in the constructor, rather than relying on globals.