Overwatch DLC is now available for Xbox 360 owners for 400 MS points and on Playstation store for $4.99, This DLC has missions for Single Player, Co-op and multiplayer as well.
The Single Player, Co-op has two missions:
Freindly Skies: You would have to defend freindly reinforcements from enemy air attack to allow them to land safely.
Hostile Takeover: Set in the Armudan Villagehas gritty urban combat campaign.
For Multiplayer, you have another set of 2 missions
Blindside: focuses on the PLA making rapid advancement to some objectives, while the US Marines needs to defend them.
Supremacy: Team Based Deathmatch with combined force multiplayers, like air strikes and heavy guns.