While upgrading home machines, my wife and I bought an upgrade machine for her that was in fact 64 bit. I figured these days that the primary hurdle had been jumped and most hardware and software supported the 64 bit vista platform. What transpired was that it was mostly true, save for Palm. After checking (way after buying the hardware), Palm (and their OS provider "Access") are quite adamant about the lack of support for the 64 bit OS.
Specifically, this is due to the USB charging / synchronization cable, but even attempting to use a Kensington USB Bluetooth dongle failed to allow syncing the Palm with Vista 64. The return on investment is not enough to justify my continuous battle with the synching process; the current plan is for her to use our laptop to do so.
What's amazing to me however is not only that it didn't synch, but that it didn't even cross my mind to check, even after seeing the "64 bit OS installed" sticker on the machine on the Best Buy display. Clearly the platform / architecture even still has room to grow with respect to driver support!