If you're into wxPython, this is a must have

Unfortunately, this is the only game in town, so the mistakes, omissions (like MultiMedia), etc., have to be accepted.

That said, it is a good introduction to the subject, even though you need to understand GUI-programming, OO, Python and a bit of wxWidgets beforehand. But at least it is a lot easier to read than many Java books :-), but it is not a reference book, more of a quick overview.