PyQt is a python interface to Qt. More information on PyQt can be found at it's home page. More information on Qt is found at TrollTech.
Qt is great because it is written natively in C++, plus extends it with signals and slots. Signals and slots greatly simplifies the task of writing and using callbacks. Qt also comes with excellent documentation.
Python is great because... well, if you don't think it is great, it is probably because you haven't written much with it. It is easy to write, easier to read, and makes managing large projects a lot easier.