It is probably after watching the video made by John Hillcoat that Brad Pitt got hooked to an adaptation of this game. But i think really has to check out the writings of Cormac McCarthy to really get into the world of the Western.
Red Dead Redemption regardless is a good game, but an adaptation will still be difficult for Hollywood to imagine. Brad Pitt is still looking out to find ways to adapt this classic game. It is still not clear who has the rights to this game.
The Western is getting a revival of sorts this year with two directors working on two different types of Western. Jon Favreau is working on Cowboys and Aliens while the talented Coen Brothers will be doing True Grit.
Brad Pitt is still associated to a lot of movies so this development could die down in days. We will keep you posted on this.