If you’ve played the hell out of ‘The Passing’ and ‘The Sacrifice’ then you’ll be happy to know that more DLC is coming to Left 4 Dead 2. On top of adding the 3 remaining campaigns from the original Left 4 Dead, this DLC will also include a brand new campaign.
‘Cold Stream’ is the name of the new campaign and it’s being developed by Matthew Lourdelet by way of modding. Valve saw the impressive amount of work going into this campaign so they’re going to be officially releasing it as DLC for PC, Mac, and 360 owners of the game. While the previous two Left 4 Dead 2 DLC campaigns were story-oriented, ‘Cold Stream’ will not be. Instead, the focus is on pure game-play, with the inclusion of “innovative game-play arenas and effects”.
There’s no firm release date for this upcoming DLC, but Valve states that it’ll be hitting after Portal 2.
[Source]