Well in their wisdom, Infinity Ward have decided NOT to allow dedicated servers for the next instalment of CoD.
This means no one can set up a server, you have to play via IWNet, which decides where and with whom you play.
After seeing the evidence so far, you'll be lucky if you can get 6v6 games.
This is due to the fact, you'll need to rely on the upload bandwidth of one of the players, as you'll be using his PC to host the game.
Now it seems PS3 players are up in arms, due to the fact they have restricted hardcore modes, plus some are also asking for dedicated servers.
Info about dedi servers can be found here.
The petition can be found here.
I personally have stopped my pre-order and will not be buying the game, unless this situation changes.
I know of many others that feel the same way.
This link show a search for the word boycott, in servers already in place.
Edit: A blog from fourzerotwo on the subject
I'm not a happy gamer atm, been waiting for this game for some time, infact since CoD4.