The 2 player co-op mode in Modern Warfare 2, is of course called Special Ops. From the news of 69 stars available in this mode (1 star for completing it on Regular, 2 for Hardened and 3 for Veteran), we know we have 23 different missions. A quick google gives us these at the moment:
•Breach and Clear
•O Cristo Redentor
•Sniper Fi
•Hidden
•Suspension
•Body Count
•Acceptable Losses
•Bomb Squad
•Estate Takedown
•Time Trial
•The Pit
•Snatch & Grab
•Terminal
•Wreckage
•Overwatch
•Big Brother
•Evasion
•Race
•Homeland Security
•Wardriving
Couple of other nuggets:-
•The coop mode will feature the Juggernaut, an enemy with massive amounts of armour that will require a headshot or lots of firepower to bring down.
•Special Ops has 5 groups (Alpha, Bravo, Charlie, Delta, and Echo). It takes 14 stars to open the next group.