Windows 7 Team officially released 14 new themes 3 days back for its users. Currently many people are using its Beta, RC and RTM releases. You may also check out the latest themes, gadgets, desktop backgruonds, and slideshow gadgets in this link.
You can see the themes are sponsored themes from their names 🙂 Yes, the brands are Pepsi, Coca Cola, Ferrari, Gears of War (Game), Infiniti and some microsoft products like Zune and Bing. Enjoy downloading the windows 7 stuffs.