It seems that Infinity Ward isn't fucking around with cheaters. Just like EA, IW has started banning players using exploits or glitches inside Modern Warfare 3. They are also working on a title update to resolve those issues.
Tweeted by Infinity Ward's Robert Bowling, they have only banned a bit over 1,600 people, which isn't a lot of people seeing as they have sold millions of copies already. But these 1,600 plus people are the example of what happens when you cheat.