The Stinger returns in Call of Duty: Modern Warfare 2 for the same purpose as the first game. In the campaign, it is used in the mission Wolverines! to shoot down enemy Helicopters. It can also be found in The Only Easy Day...Was Yesterday and can be used to destroy an enemy Helicopter.
The Stinger is available in multiplayer as a secondary weapon, unlocked at level 30. It can lock onto killstreak vehicles and comes with two missiles. It can only be fired at killstreaks, and not other players.