The upcoming "Cold Stream" DLC for Left 4 Dead 2 features a new community-created-and-tested map along with three maps from the original Left 4 Dead: Blood Harvest, Death Toll, Crash Course and Dead Air. The original map, Cold Stream, was submitted via the Valve community and beta-tested for a better part of a year across Xbox 360 and PC.
The DLC comes out cross-system wide on July 24th, making all the Mutation modes includng "Taaank!!," which is like Survivors vs. Infected multiplayer, but every single Zombie is a Tank class. Hence the yelling, exclaimation points and general dread. And it'll also allow Xbox players to try their hand at "Confogol," a user-created mod that balances the weapons and items ratio along with giving an edge toward the Infected.
There's no confirmation on the price as of yet.
via Left 4 Dead blog