I'd really like to hear some non-enginners perspective on how this is working. Everything I've heard about GitHub is really positive from engineers but less so from its other members.
I read this article today: "How Google Sold Its Engineers on Management" 1), which seems to be a much bigger study of how managers affect work and performance. The general conclusion of Google's study is that management matters if it's empowering workers (and not micro managing them).
Github is definitely an interesting experiment in a totally flat structure. Google tried a similar flat structure in 2002, but concluded that it did not work that well. Will be interesting to see how it works for Github as they grow even bigger.
One of the problems I see with Github structure is firing people. One of the tips you see most successful companies follow is hire slow and fire fast. I think it's unrealistic that every hire you do will be the perfect match and a lot of times things just don't work out. The question is: how does Github handle this case?