Just played COD4 on the PS3 and have to say i was pretty surprised. There was NO lag, it was quicker to get into games than the 360, but it looked exactly the same (expected PS3 version to look better).
The main difference i noticed is how the PS3 version is 'faster' than the 360. Its like the speed is turned up a notch, and the gameplay is quicker.
Also i noticed they dont play the same as the 360 players lol. Every game i got into, people were everywhere, and not sniping, not camping - they were bloody behind you, coming to your left, right and bloody above you.
I seriously cant get used to the controller though, the shoulder buttons are opposite ways, and the left stick is positioned differently, but im sure ill get used to it.
Managed to get to rank 8 i think in an hour, and i was doing badly till the last game and got 22 kills and 4 deaths.
Another strange thing is.. its awfully quiet. NOONE uses a mic lol except the odd one or two - which sounded like robots
After playing.. im starting to think what was i paying Microsoft for the gold account... there was no difference at all!