As if PC players weren’t already up in arms about Modern Warfare 2. People have been taking notice that on the Steam page of the game it states that it will be available on November 13, three days after official release.

However, retailers such as Amazon and Gamestop still have the PC version of the game shipping on the 10th. So it seems if you want to play MW2 on the day of release, Steam will not be the way of getting it. Either going to a store, or ordering it online for delivery looks like your best bet.
Modern Warfare 2 Page [Steam]
