This is a few days old, but better late than never: Joystiq has interviewed Infinity Ward's lead multiplayer designer, Todd Alderman. The interview took place last week at the multiplayer event and there are a few interesting questions in there.
Can anybody use that riot shield or is it just that class?
It is a primary weapon. So you can choose to take an M4 or you can choose to take a riot shield. What you are giving up with that is your primary weapon. So when you have the riot shield out, you can't shoot. All you are doing is blocking. You can kill the other guy with melee, but it takes two hits. Like the knife is an instant kill; one hit, he dies. With the riot shield you bash him with the shield and then you bash him again. Then they die. So it is much harder to kill someone, but it is really satisfying.
Can you describe what spec ops is really quick?
Spec Ops is ... you have your campaign, which is the story. You have your multiplayer, which is the online stuff. And then you have Spec Ops. These are like standalone missions that you can play by yourself or with a friend in split screen or over the Internet. This is the best analogy, Airplane from the last game, it is a short mission and there are just a lot of these. They are missions that aren't tied to the story, but there are a great variety of different locations, different types of missions. You will do things that you can't do in multiplayer and you can't do in single player.
You can read the rest of the interview at Joystiq.