Ok, so, yeah, I'm one of the Infinity Ward programmers. I won't even pretend to be objective about our game, because all of us at IW love it (duh). That said, I see some questions coming up repeatedly in various threads...
1) We don't support keyboard and mouse on PS3, sorry.
2) No rumble (DS3) support - we found out about it too late to add it to this game. Hopefully next time around, though!
2) Yes, the PS3 version does support voice chat (bluetooth and USB mics supported.)
3) There are minor visual differences between the 360 and PS3 versions, due to the platforms being extremely different from an architectural standpoint. This results in us having to make different tradeoffs on both platforms to hit our framerate targets. They're very nearly identical, but you'll be able to pick screenshots in which both versions are "clearly" the better version. They're as close as we could make them without going completely batcrap insane (though whether or not we are already completely batcrap insane is a matter of some debate.)
Tradeoff example: Shadow filtering. We use different techniques on PS3 and 360 to filter shadow edges, which gives them a bit of a different look. I think it's a matter of taste as to which way looks better, but we did it that way because it was the most efficient way to do it on both platforms that yielded a look that was good enough.