The Grammar of Fun - A Look at Gears 2 and Cliff Bleszinski
If you are looking for a really interesting read on Gears of War 2, and more specifically the game's lead designer Cliff Bleszinski - look no further than this lengthy New Yorker Article. Granted there's no specifics of cooperative play discussed, but that doesn't make it any less a worthwhile read while hyping yourself up for the co-op shooter.