Dennis Hotson has a new post to his Tumblr blog about what he calls PHP object-oriented programming reinvented - a chunk of code he's created that lets you build classes out of objects.
It's tentatively called "PHP Object Oriented Programming Reinvented". Although it turns out the acronym is kind of unfortunate. I'm still working on that... The main idea is that classes aren't really very special at all, they're just objects like everything else. They don't even have names.. you give your class a name by giving the variable it's assigned to a name.
He includes a code snippet that shows the creation of a sample class (the "class" class) and extend it with a new class of "animal"....and then extend that with a class for a "dog". You can take a look at the full code for the method here.