Treyarch will reportedly be introducing a new matchmaking system in Call of Duty: Black Ops 2, a more competition-minded framework that layers on top of the existing one, according to an anonymous tipster (via Examiner). The added ranking system will allow players to be matched with those of like skill levels based on their win/loss ratio, much like Halo does.
It sounds like the old method of being matched based on your XP total will still be an option, but this new approach offers more value for competition-minded players. An added component will see players being placed into "leagues" after their relative skill level has been determined over the course of four placement matches. None of this has been confirmed, but it does line up with some of the rumors we've heard about Black Ops 2 offering more of a pro gamer-friendly experience.