FOSSMMO
To create an open source and openly developed mmorpg
...The first is to create an open sourced MMORPG with compelling and fun gameplay requiring modest system specs. The second is to develop in an open and well documented way to help others learn the trade of game programming.
FOSSMMO will be developed using python. While python is not a common language for game development I'm a fan. Also I recently watched http://pyvideo.org/video/381/pycon-2011--algorithmic-generation-of-opengl-geom which looked amazingly fun and is influencing my selection.