A number of sites have done a post-mortem on the Mountain Dew WoW Game Fuel ad (featuring two ladies battling it out through their WoW characters in a live-action supermarket), and they've uncovered a really interesting fact: the ad was actually directed by Indian director Tarsem Singh, one of my favorites -- he not only did the visually stunning sci-fi/horror flick The Cell a few years ago, but more recently made The Fall, which is an very well-done kind of mirror-life fairy tale. He's directed a number of commercials before, including some for Nike and Levi's, and teamed up with a company called Zoic Studios (they've done a few other spots for video games already) for this WoW commercial.
The original CGI models for the ad did come from Blizzard (I'd guess that they're the original models from the WoW CGI trailer), though they were spruced up quite a bit by Zoic to add facial expressions and dynamic costumes and hair. They were then connected to motion captures from stunt artists (which were probably also tweaked to seem a little more than human, and then composited all together in the supermarket scene.
Very cool stuff. This isn't the first time WoW characters have been used to sell soda, but hopefully we'll see more fun sequences like this come out of the deals between Blizzard and their partners.