This post by Yee Lee (framethink) gathers some impressive and informative impressions on the developer culture in Facebook. There appears to be a kind of constant pressure to perform up to and exceeding the expectations of peers and peer-managers. It must be mentioned of course that it appears to take place in a highly 'visible' work environment, but one that values responsibility over correctness, a kind of risk laden work style that attempts to avoid the reactive response to risk-aversion. How this kind of working style acts to support individual skill growth, career development and team oriented activities is still open to question.
See article at FrameThink