GameStop website says Colonial Marines is shipping 12/31/09...
It's cloudy as far as I can tell... I google a bit and half the pages are "Has Colonial Marines been cancelled?" with no one seemingly having reliable information.
I hope it does get made... What good is having a gaming nerd for a girlfriend if no one makes games you can actually play together?

Resistance 1 was great, but then they botched the co-op in Resistance 2, and Call of Duty: World at War was annoying too (it made me beat the 1 player campaign before we could move on in the 2 player campaign).
(PS3, by the way).