You should also add the updates feed to your RSS reader to get notifications when new versions come out.Older Versions: Demo App Binaries:
Chipmunk2D's C source can be checked out from it's Github project
Chipmunk2D Pro customers have read-only access to our private Git repository. You just need to use the login/password you obtained when you purchased it.
git clone --recursive http://myLogin@chipmunk-physics.net/release/chipmunkPro/ChipmunkPro.git