Stephan's had us do this drill in warmups before, and watching guys like Ryan Hall, Tommy, and Clint--guys who spend a lot of time in the guard--over the past several months has only underscored how important this move is.
There's picture in The Essential Guard of Rodrigo Medeiros doing what he calls the "compass drill" that looks very similar, involving a shoulder roll. But there's probably a better copy of the granby roll in this Google Video.
