A Python module (a set of classes) for doing interactive 3D animation. VPython has at its core a module called Visual, developed originally at Carnegie Mellon. Outside of graphic primitives, VPyton provides vector operators. It is distributed together with a fast mathematical toolkit. The module runs under Windows, Linux and the Macintosh, in Python 2.2. It requires OpenGL, which means that it will use graphics hardware when it finds it.
I am investigating it because I am looking for an interesting, non-textual form of output for Python: not all people learn well when the output is only text, and I would rather not expose beginners to the Tkinter Tcl/Tk module immediately.
The module is well documented, and it has not died on me yet. Rather impressive results are obtained with little effort, and the object hierarchy is easy to understand, while mapping well to 3D graphics theory.
The module has been written up in:
Scherer, D., Dubois, P., & Sherwood, B. (2000). VPython: 3D Interactive Scientific Graphics for Students, Computing in Science and Engineering, Sept./Oct. 2000, 82-88.
And the website is http://www.vpython.org/