Left 4 Dead add-on Crash Course has been released on Steam and Xbox Live Marketplace, as Valve said it would be.
Valve didn't tell us the Xbox 360 version would cost 800 MS Points (£6.80/9.60), however - 560 MSP (£4.76 / 6.72) was the previously announced price. It's not clear whether this is intended or simply an error. Tom's downloading the add-on for Xbox 360 now.
Update: Xbox Live's Larry "Major Nelson" Hryb has Tweeted that the higher price-point is an error, and the content should cost 560 MSP. He suggests holding off until Xbox Live admins rectify the mistake.
PC owners needn't pay anything for Crash Course from Steam, although the DLC doesn't appear to be available just yet.
Crash Course bridges the gap between the No Mercy and Death Toll campaigns in the original game, and has been designed for shorter, 30-minute Versus mode games, as matches using the existing campaigns can take around two hours to complete.