Army has been developing a GPL'd CAD package since 1979: BRL-CAD
brlcad.org
Can't believe I'm submitting this to you guys three days after GSoC applications closed.
brlcad.org
Downloading now. Wonder if it still has the horrid text based interface.
Of course, I played with it for about 15 minutes before giving up.
If you really want to work on an awesome government program that was released to the public domain, OpenVISTA could use your help: http://sourceforge.net/projects/openvista There's not higher calling than helping people live healthier and saving some lives.