Very cool! I'd pinged GitHub's bizdev team to ask about a developer program a few months back and was told that something was in the works. I'm impressed with what they have so up and running so far.
Question for anyone from GH who's reading this - will there be documentation released for how to integrate with GH Enterprise? I imagine there are some implementation details (e.g. OAuth access) that differ between regular GH and a GH enterprise install.