Valve has confirmed the Cold Stream DLC for Left 4 Dead 2 will be available on Xbox 360 and PC from July 24.
The content pack features the new community-made campaign, Cold Stream, along with classic maps Death Toll, Dead Air, Blood Harvest and Crash Course.
On the official L4D Blog Valve also teased some new announcements but didn't go into detail, instead pulling a bait and switch by revealing that mutations will now be available all the time.
"There are some other surprises and details we will give you later but for now we just want to confirm an often requested feature. With the update going out at the same time (also for the PC), all of the mutations will be available at all times. This will allow players to choose to match into games playing Taannkk!, Gib Fest, or even a user created mutation like Confogl."
Payday: The Heist developer Overkill Entertainment has announced it's collaborating with Valve to create a "very cool blend of Payday and Left 4 Dead".