At the Mozilla "Web Rendering" work week in Taipei in May, I led a discussion of "Mozilla (really, Gecko) engineering culture". This was partly for the benefit of all the new developers in Taiwan but I think it was interesting for many of the old hands too. The talk is now available on Air Mozilla. It's excruciating to watch myself talk, but people may find it interesting.
It wasn't initially intended for public consumption, but after reviewing it I thought "why not?". So it's a pretty honest snapshot of Mozilla developers explaining what we do.