It's a headset adapter called the turncoat that eliminates the star nut and allows the front brake cable to route through the steer tube. It's a part that should be coming out for the 2011 season, but was only available to Blackbox project riders.
Trail: Home Riders: None Description: Good picture of the new 2011 Rock Shox TurnCoat headset adaptor at work on my Specialized SX. Completely eliminates the star nut, and uses special top and bottom caps to allow the front brake cable to run tangle free through the steer tube for barspins and tailwhips.