I've got nothing against fast zombies (the opening sequence to 28 Weeks Later is terrifying). And standing on its own, this trailer looks awesome. However, calling it "World War Z" makes me a bit disappointed. It seems like they just bought the rights just so that they could slap the title on their own zombie movie.
That being said, I'll still see it. And I hope they do a trilogy that covers the scope of the book: outbreak, living in a zombie world, and retaking the planet.