[UPHPU] Looking for a good OOP PHP5 App for learning purposes

[Jonathan Duncan]

I would like to know from anyone if they have or have seen a really well 
written PHP app that uses PHP5 and is as OO as possible.  Something you 
have been impressed with, from a code standpoing.  If you have, please let 
me know.  I am looking for ways to enhance my PHP skillz and having a good 
working model to study could be quite helpful for me.

Currently I am digging through different frameworks to see what they can 
offer me in the way of optimizing and enhancing my skillz.

Thanks,
Jonathan