Wolfe has a short (1 page) commentary in the 2002 Nebula Awards Showcase (edited by KS Robinson). It's basically his response and updating of Knight's famous remark that we have had the future of the golden age SF writers.
He also apparently has written an appreciation of Lafferty in the current (May) issue of Locus, which I haven't seen a copy of yet, and which is not on the Web like "Joe and Me." (Neil Gaiman and Terry Bisson also have written appreciations.)
-Jeff Prucher