New study here.  It was prompted by some of the moves since the 2007 study of highly cited law faculties (Sunstein's move from Chicago to Harvard, and now to the Obama Administration; Chemerinsky's move from Duke to UC Irvine; Lessig's move from Stanford to Harvard; Epstein's decision to formally split his time between Chicago and NYU; among others), which has led various folks to wonder whether that would change the profile of faculties with the most scholarly impact.  There are, indeed, some notable changes, though a fair degree of stability as well.