"PyPy is an implementation of the Python programming language written in Python itself, flexible and easy to experiment with."
Project home Page: http://codespeak.net/pypy/dist/pypy/doc/
More information at:
Current Release: 1.1
Supported across Linux, OS/X, Win, .NET and Java.
Supported via several mailing lists, bug tracker, and irc channel.
Pypy does not seem to be an appropriate solution for executing python code on microcontrollers
From wikipedia:
"PyPy was conceived as an implementation of Python written in Python, which enables Python developers to hack the implementation. This makes it easy to identify areas where it can be improved. PyPy is also more flexible and easier to experiment with than CPython, thus allowing developers to experiment with multiple implementations of specific features.