(via) PyPy had its 1.0 release recently.
Now, This looks *really* interesting:
PyPy Stackless
PyPy can expose to its user language features similar to the ones present in Stackless Python: no recursion depth limit, and the ability to write code in a massively concurrent style. It actually exposes three different paradigms to choose from:
Tasklets and Channels Greenlets Plain Coroutines
Copyright © 2006-2008 Corey Goldberg
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.