Infinity Ward is aware of the problematic hack issues of the PlayStation 3, regarding Call of Duty 4. They also investigating the glitchers. This is what Infinity Ward just tweet on Twitter:
"Thanks for all the feedback from our COD4 PS3 users. We hear you loud and clear and are investigating the glitchers. (via @fourzerotwo)"
*Please do report all cheaters to Sony. When doing so PLEASE remain calm. Abusive reports do no good and you risk being ignored or reprimanded by Sony. Being calm is the best way to address this situation.