In an attempt to combat cheating and code exploits, Rockstar has issued a patch today for the Xbox 360 version of GTA 4. The cheating apparently has been letting players turn invisible and use cheat codes to sway the game in their favor.
It’s been quite some time since I played GTA 4 online so I have yet to see any of this cheating. It also maybe hard to detect if you don’t know what to look for.
The update should prompt as soon as you load up your copy of GTA 4.