Nope. Just confirmed with mojombo that it's legit. He's just showing GitHub off to family :)
404, now. What did we miss?
A repository named 'mojombo/fakkkkkke', with commits from another user account. Just a standard test repository, nothing amazing. Turns out the user was a family member.
Wow and they seriously used the word "Hacked"? Whoever submitted this is an idiot, this is basic GitHub functionality.
I think the point was this is a Github staff member (with 9,000+ followers) so a "random" repository turning up (in public, with no indication it's to do with the github staff member) seems odd.