Check out the full rundown of the prizes on offer here. Included is the scale model Walker you can see there on the left.
To be in the running to win, you have to submit a photo demonstratiing your support for the Red Faction. It must be a real photo - preferably of you. It must be taken in a public place - i.e. not your bedroom. And it must include, in some way, shape or form, the Red Faction Hammer logo - the symbol of the revolution (pictured at a higher res in the original post).
You also stand to win this bloody great big hammer.