Wow, that sounds great! Thanks a lot for all your efforts!
Bitbucket is a great way to share the source, definitely stick with that.
To make it easy to find for users, you could put a description and a quick how-to in the Sparrow Wiki!
BTW, we'll probably get a Chipmunk wrapper, too, in the near future — Rob Carone is working on that right now. With this and your extension, it will finally be really easy for developers to create physics-based Sparrow games. You're making us birds really happy! 😎