It's been around for a while but this powerpoint (linked directly as a *.ppt) is a presentation from Marc Lucovsky about the development process of the early iterations of Windows NT to Windows 2000.

Interesting things:
+ NT 3.1 was ~3 years late (I'm not feeling so bad about being behind on my current project)
+ The original team was only 6 people from DEC. That's astonishing. The eventual development team size was 200 with 140 people on the test team.
+ Quotes:
"To scale a development team, you need to establish a culture"
"Sloppiness is not tolerated"

+ By Windows 2000, the development team was 1400. I wonder what Vista's team size is?
+ The evolution of source control and branching at Microsoft.