Paragon Machine Works brought their entire catalog to the 2011 NAHBS. Included on their table were the new Rocker dropouts. These fix alignment issues faced while using disk brakes on a single speed bike. They can be used for adjustable chainstay frames, internally geared hubs, belt drives and other applications where there are advantages to being able to move the rear wheel with a brake caliper.
Check out a slideshow from my coverage of the 2011 NAHBS Paragon Machine Works booth below!
These photos are also at my Flickr!