DiRT 2 PC US Shipping Date on the Codemasters Forum is a post from community coordinator Ice, who updates the US release date for the Windows version of the rally racing sequel (thanks Derek). During the summer it was revealed the Windows edition of Colin McRae DiRT 2 was delayed to December to implement DirectX 11 support, and while a specific date was not mentioned, this post addresses the premise the game was due on December 1, saying:

Hi Guys a lot of people have been asking what happened to the US release date of 1st Dec. I've had it confirmed from our US office that the shipping date has been moved from 1st Dec to 8th Dec.

This is not due to a technical issue in any way shape or form. The actual reason is far to boring to go into to be honest.