I am curious. Do the 1-series dSLR's, which are clearly geared for professional users, have Direct Print buttons as well? Do professional photographers actually ever use this button/feature? I understand Canon placing this button/feature on the entry-level bodies and even maybe the prosumer level cameras, but if the majority of professionals do not care for it, why should it make its way on a professional or semi-pro level camera?
It is an improvement that the 50D's Direct Print button doubles as a trigger for Live View mode (is this through custom functions?), but for this new 5D MkII (or whatever it turns out to be), I would like to see it replaced completely. It could be something like a Live View/MLU button instead.
Personally, I would be very fond of a "Kick-Ass" or "Obliterate" button. 