Codemasters has announced DiRT 3 has ditched Games for Windows live for Steamworks. All who own the game on PC will be upgraded to the Complete Edition, which includes all DLC at no extra cost.
Those who have the GFWL version of DiRT 3 in their Steam Library will now have access to the DiRT 3 Complete Edition in the owned games list. Just click it to install.
If players own the physical copy or have a GFWL key, it can now be activated on Steam.
The only caveat to this, is the GFWL save files are not compatible with the Steam version. This means progress will not transfer over.
Finally, those who use Mac will now have access to the DiRT 3 Complete Edition via Steam as well.
More information is available through the link.