I actually just ran into a few in Domination, ones that I know were hacking for sure, even caught it in my Theater Mode:
Personally, I think calling them "hackers" is giving them too much credit. I prefer the term "Script Kiddies", it much more accurately describes them. I sent this video to Candice and IWEnforcers, so hopefully these kids will get perma-banned (for all the good it'll do since on PS3 it takes but a moment to make a new account, perhaps an IP ban is in order, or on their console completely?).