So, I came upon this from /.
iPhone not supported under 64-bit Windows XP or Vista
Pretty dumb, I think, since all Windows versions henceforth will supposedly be 64-bit. 2/3 of my computers are 64-bit processors. Of course, right now I’m running 32-bit Vista on those computers because of all of that driver signing crap.
I think eventually, though, it will be supported. Perhaps they just felt they had to get it out there…Windows being an afterthought, of course, next to OS X.