It seems according to this link that Crash Course is going to be out on the 23rd of September. Valve has released this date as a possible date for the release but it seems since xbox has setup a “Game With Fame” event around it. So it seems it’s a little more permanent than valve is letting on.

The “Game with Fame” is a thing that Xbox is doing where you log on and play games with famous people. The Crash Course GWF is with Paramore a Rock Band from Tennessee.
Update September 28, 2009 1:02 PM

Okay so it seems crash course is going to come out Tuesday the 29th. Which is tomorrow. YAY