With Xbox 360, Microsoft is launching a new version of matchmaking for 360 games. This system will be the same on all Xbox 360 games, unlike games for the Xbox, where you had for an instance Halo 2's wonderful matchmaking system, and then you had Counter-Strike's lousy system.
The system is based on ELO, which is used by chessplayers.
Read more about it here!
It's really interesting to see how much the matchmaking system has developed.
Oh and I posted this for people to see and be informed.