http://github.com/bamboo/boo provides a web interface for browsing the source code currently in GIT.
The code of the project can be checked out by anyone through anonymous git server access with the following command:
git clone http://github.com/bamboo/boo.git boo
Notice however that this will get the latest development bits and some of the test cases might fail. However if you want to work with the most up to minute version, this is what you will need to check out.
(ask bamboo directly)