pybox2d 2D Game Physics for Python https://github.com/pybox2d/pybox2d
pybox2d is a 2D physics library for your games and simulation. It's based on the Box2D library, written in C++. It supports several shape types (circle, polygon, thin line segments), and quite a few joint types (revolute, prismatic, wheel, etc.).
For building instructions, see INSTALL or the wiki on the homepage. Once installed, check out the testbed demos to see what pybox2d can do (located in examples/ ). Then read the manual located on the pybox2d wiki, here:
http://code.google.com/p/pybox2d/wiki/GettingStartedManual
On the wiki, you will also find more useful things of varying quality. Here's the epydoc documentation:
http://pybox2d.googlecode.com/svn/doc/epydoc/index.html
It's by no means perfect, but it can come in handy.
Please submit any bugs that you find to:
https://github.com/pybox2d/pybox2d/issues