A very easy to use and powerful Python interface to the Simple Directmedia Library (SDL) platform independent graphic, audio and input libraries.
There are numerous examples, and the documentation is very good. You'll be surprised at how easy it is to write games or other graphics-intensive programs with it.
You can find it at http://www.pygame.org
"Making Games with Python & Pygame" -- A free book covering Python and Pygame
Beginning Game Development with Python and Pygame -- A new book discussing game development using Pygame
Yet Another PyGame tutorial - OOP approach!!
There is a GUI toolkit based on Pygame called OcempGUI.
See also PythonGames