Howdy, Latexmk 4.22b has been released. It will detect biber use (using the backend=biber option to the biblatex package) with the latest version of biber, 0.7.2. I've created a packaging for TeXShop which is Latexmk422bTeXShop.zip available at <http://public.me.com/herbs2>. Good Luck, Herb Schulz (herbs at wideopenwest dot com)