In this video you can can clearly see an Xbox 360 gamers making use of hacks such as walking AC-130's, infinite ammo, superspeed and many more:
So guys, MW3 lobbies are possible on xbox 360 console due to recent leaks etc. In the video you'll see me who's fallen victim to the de-ranking of the guys doing these lobbies who are running around with Walking AC130 Walking Reapers IMS etc unlimited ammo." - Ecko