The Left 4 Dead developers have announced that the game's Cold Stream expansion will be hitting Xbox 360 and PC versions of the game on July 24.

"After months *cough*year*cough* of play testing not just the Cold Stream campaign on the PC but the entire DLC consisting of Blood Harvest, Crash Course, Cold Stream, Dead Air, and Death Toll, we are ready to release on the Xbox 360," a blog post reads.

"The date will be July 24th. 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."

Besides the Cold Stream campaign and the Blood Harvest, Crash Course, Dead Air, and Death Toll levels, we've got no idea what the "surprises" could be. Any guesses? Tell us in the comments or on Twitter.