We can check one item off of Valve's forever in development list as the Cold Stream DLC for Left 4 Dead 2 will arrive on July 24th. The DLC contains the Cold Stream campaign and the Blood Harvest, Crash Course, Dead Air, and Death Toll campaigns from the first L4D. Valve will also allow gamers to play as any Mutation when starting a match, instead of going with whatever is selected for that week. This allows you to select user created ones as well, so you are not limited to what is included in L4D2. The studio teases some other details and surprises it will reveal closer to Cold Stream's launch, but it is anyone's guess as to what those are. I doubt it will be a sneak peek of a couple of other items relating to Half-Life, but hey, we can dream, right?