Frank Kleine writes a PHP 5 framework called Stubbles. I have a long-standing view about frameworks that hasn't changed one bit. But instead of arguing about the Sysaphean task Frank is engaging in, I'll show what my approach is to one small component (while being a bit jealous that he can actually develop in PHP 5).
Frank's solution involves storing the objects in the session, serializing them first. The issue comes up when the class(es) the object needs aren't included into the page. Terry offers a different sort of solution - one also using __autoload, but using it combined with unserialize_callback_func.
Terry compares this with Frank's approach and notes that his method "closes off" the system from the very PHP functions that could make his life simpler (making a separate handling system). He also includes a method for doing the same when all you know is the class file's name (non-PEAR format).