http://www.machinima.com/film/view&id=42271
One of the common themes in the series is Valve's frequent choice to delay shipping in order to get things right. Gabe Newell says something like, "Your software is late for a while, but it's bad forever." As far as I can tell, this has worked extremely well for them.
Which makes me wonder what the difference is between Valve's games and Gmail. I think it has something to do with their games being about experiential storytelling, and Gmail is a tool to accomplish tasks. I imagine most software falls somewhere on a spectrum between the "tool" and "experience" endpoints and I wonder if other software besides games might be hurt more than helped by "release early and often."