Perhaps I missed this in earlier editions, but according to my ALA Editions Spring/Summer 2007 catalog that arrived a few days ago I see that AACR2r is an ALA Bestseller! [That ! is their's, not mine.]
While I have no doubt that this is factually true—my guess is that it is even their biggest bestseller of all time—just what information is that knowledge supposed to convey to me, or anyone else?
Telling me that Carrie Russell’s Complete Copyright: An Everyday Guide for Librarians, or even that Robert Maxwell’s Maxwell’s Handbook for AACR2: Explaining and Illustrating the Anglo-American Cataloguing Rules, through the 2003 Update are bestsellers actually tells me something.
I’ll leave it up to you to determine whether and what the knowledge that AACR2r is a bestseller imparts to you and whether it is useful, or positive.