Valve has set up a website dedicated to the Midnight Riders, the rock band whose light show saves the day in Left 4 Dead 2's Dark Carnival campaign.
Meanwhile, an enterprising young so-and-so on the Valve forums has uncovered a Jimmy Gibbs Jr. zombie hidden in the L4D2 game files - Gibbs Jr. being central to the opening campaign, Dead Center - and found a way to reintegrate him. There's even some dialogue for the survivors.
None of that will make much sense if you haven't played Left 4 Dead 2, which you can do now on PC and from tomorrow on Xbox 360. Check out our Left 4 Dead 2 review to find out why that's an excellent idea.