If you haven't seen this yet, on Monday Tor Books revealed the cover for Sanderson's upcoming sequel to the New York Times bestselling The Way of Kings. The artwork is by renowned artist Michael Whelan.
Words of Radiance is currently scheduled for release in March, 2014.
Michael Whelan has been one of my favorite artists for several decades and is responsible for dozens of amazing Sci-Fi and Fantasy books covers. For insight on how he created the cover for Words of Radiance, see this post on Tor.com.