Digsby is Windows only b/c Mac and Linux have been "coming soon" forever. And even if Digbsy is released for the Mac, Adium has the multi-IM space tied up on that platform. IMHO, Adium users aren't going to be switching to Digsby.
Huh? The Kuler Dashboard widget doesn't use Apollo at all -- in any way, shape or form. Now, Apollo for desktop widgets has potential -- and we're all excited about it -- but let's not get ahead of ourselves. The desktop widget is not an Apollo creation.