This just reminded me of whatthecommit.
IIRC they get these from actual commit messages; if they do, there is no hope. :-)
(edit: He made this change after a lot of discussion with a bunch of people, and he also sent out a mass email describing the changes to the structure, so he wasn't totally being irresponsible there.)
I'd assume the keys are the commit hashes? Now how to search github for them...