GNOME Shell is the window manager (and some would argue a little bit more) for G...

GNOME Shell is the window manager (and some would argue a little bit more) for GNOME3. The GNOME wiki is a good place to start. A mostly up-to-date design overview is available at https://live.gnome.org/GnomeShell/Design/

A technical overview can be found at Owen Taylor's blog http://blog.fishsoup.net/2008/10/22/implementing-the-next-gn... It's old, from when the shell was just being planned, but all the major architectural decisions are there.