Left 4 Dead 2's Cold Stream DLC is here. Well not here, but there, on your PC or Mac, having surreptitiously downloaded itself while you were fast asleep in bed, creeping on to your hard drive like a digital out of season Santa Claus. The free DLC, which has been in public beta since the dawn of time, officially ports the original Left 4 Dead's campaigns into Left 4 Dead 2, while also adding the community-created Cold Stream campaign. It also introduces a dash of a sprinkling of additional stuff, like freely available mutations, the ability to import L4D characters into the Source Filmmaker, and more! More!
Not strictly part of the Cold Stream DLC, the Left 4 Dead devs are today highlighting the Deathcraft II community campaign, which total-converts Left 4 Dead 2 into Minecraft. Valve are also making available the cast of L4D2 characters in the Source Film Maker, allowing you to make a proper zombie movie by simply clicking and dragging in the right places for hours and hours and days and days.
And, if you don't actually own Left 4 Dead 2 and have been whipped into excitement by all this news, the game is currently discounted on Steam. It's almost like they know.