From the Azeroth Choppers site:
Grab a front-row seat for the ultimate road showdown! Legendary custom motorcycle designer Paul Jr. has assembled two handpicked teams of bike experts to bring to life a pair of asphalt-kicking chopper designs inspired by World of Warcraft®’s two warring factions. Joining each crew on their epic quest are members of the World of Warcraft development team, on board to help to infuse the essence of the Horde and the Alliance into each bike. In the end, only one chopper will reign supreme as the undisputed king of Azeroth’s roads in a winner-takes-all showdown voted on by World of Warcraft players around the globe.
World of Warcraft players will get to watch as the builds unfold and vote on their favorite bike.