Those hoping that Unreal Tournament 3 would be getting the Crackdown treatment by including a multiplayer beta/demo for Gears of War 2 will be disappointed to learn that there are no plans to release a demo of the game. Gears of War 2 associate producer Tanya Jessen has recently stated that the relatively short production time for a game of this caliber, two years, and that fact they they're focusing on putting out the best possible game, means they do not want to divert any resources into making what amounts to a second product, a demo.
source: http://www.shacknews.com/onearticle.x/52306