You know what always goes well? When Valve offers to release something early if only customers do something for them. That's something with a solid history. Leaping onto this unwaveringly endorsed theme once more, Valve have announced plans on the Left 4 Dead blog to release Dead Air from community-co-created Cold Stream DLC pack early if enough people bug test the new campaign for them.
This next DLC is a big one. Along with the campaign created by community member Matthew Lourdelet, they also plan to release the three remaining campaigns from the original L4D so they work in L4D2.
So if more than 20,000 people gain the "Stream Crosser" achievement, awarded for completing the beta of the new campaign, by this Sunday, they'll release L4D1 campaign Dead Air early. On 22nd July. Nothing can go wrong!
This is all only good for the PC version, which is available today (for another 8 hours) at 75% off. Which is £3.74. Which is a very tiny amount of money.