BlitzMax released for Mac OS X
Junks Jerzey writes "The long awaited long suspected-to-be-vaporware BlitzMax game programming language has been released for Mac OS X. Linux and Windows versions are set to follow "soon," making this a truly cross-platform, OpenGL-based game development system. Don't be scared by the BASIC monicker: this is a modular programming language that lets you get under the hood if you want, but also includes OOP support and higher-level features. But of course C++ game programmers will still shake their heads in a puzzled fashion, ignoring all the amazing games written by hobbyist programmers. If nothing else, write a cross-platform OpenGL demo in ten lines of code!"
To be fair to python, you can get a lot of stuff onscreen at excellent framerates, but you do have to be careful how you do it. Extensive use of vertex arrays, or at least display lists is essential, but to be honest that's the kind of thing you'd really want to be doing with C/C++ anyway, it's just that it hurts even more if you don't do it in python.
One of the other replies mentions pysco, but to be honest I think that pyrex would be more useful, as it for most intents and purposes allows you to compile sections of speed-critical python code in C.
http://www.metacard.com/
(although sold to runrev for commercial development, getting the old metacard IDE and heading over to yahoo groups, you will find some nice geeks continuing development of the free version)
http://www.hyperstudio.com/
It's been forever since they released a new version, and there is no Linux version of the software.
http://www.squeak.org/