Sounds like they probably used social engineering to get initial password(s) and thanks to poor security practices used those to go from there? Not to sound malicious or impersonal, but breaking something so wide open is like a solving a hard puzzle, I'd be really interested to hear more details on how they actually did it.
I can't stand Gawker and Gizmodo and the shit attitudes of the people there. Love to see their attitude in Basecamp and see them get owned hard. I know it's juvenile, but I'm just being honest. Now I'm going to go check and make sure I didn't have an account with them, ever.
http://pastebin.com/cpb7ndV8