We've just released our puppet repository into a public git repository. For more information, see the blog post about this:
http://blog.wikimedia.org/2011/09/19/ever-wondered-how-the-wikimedia-servers...
As noted in the blog post, we are releasing this to treat operations like a software development project. Users with Labs access can push changes to the repository. We aren't currently ready to start giving out Labs access en masse, but will hopefully have a process ready by the New Orleans hack-a-thon.
More info to come about Labs later.
- Ryan