DrawBot is a simple application for MacOSX that allows you to write simple Python scripts that generate two-dimensional graphics. The builtin graphics primitives are currently pretty braindead, it currently only supports rectangles, ovals and (bezier) paths and polygons. A future version will also support text and images.
Currently developed by JustVanRossum.
BobIppolito and BrendanHall are hacking on a DrawBot based project that includes dynamic GUI generation (using GNUStep Renaissance) and more, it will probably end up being a fork as the plans are to become a tool for designing, not so much for teaching. You can download the prototype, which includes a self-contained application and the source from the links section. Here's a screenshot:
DrawBot was first unleashed on September 29, 2003.
http://nodebox.net application that lets you create 2D visuals (static, animated or interactive) using Python
http://undefined.org/python/DrawBot_widgets1.tgz (prototype w/ Renaissance)