This was sort of fun. I wrote a batch script in elisp to rewrite some of the Emacs sources — yay semantic patching!
Thanks to Giuseppe, this is now hosted on Gitorious. We’re both working there, on different branches, merging code back and forth. I’ve mostly been working on variable bindings, and he’s very active, both with low-level changes and cool things getting Gnus to work in a separate thread.
If you’re interested in helping out, we discuss it on emacs-devel, but really we’d welcome any sort of contact.