Annoyingly, having just gone through an annoying install of Vista x64 (click), Apple has just released an updated version of the Boot Camp drivers / software which:
“addresses issues and improves compatibility with Microsoft Windows XP and Microsoft Windows Vista running on a Mac computer using Boot Camp. It is highly recommended for all Boot Camp users. “
Click the appropriate link for the version of Windows you are running to download them:
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Edit:
Have just installed this – - you shouldn’t expect anything useful like the ability to tap-click on the touchpad [can't someone mod an .inf file or something!?] or Wake on bloody LAN 
In fact, I haven’t noticed anything different at all.
According to a comment at TUAW though, it does fix the wireless [Apple] keyboard problem with the caps lock[e] 
which would be good, if this installation hadn’t broken my bluetooth…. *sigh*
Edit 2: I’ve just found out that this is the same version that was taken from the Mac Pro DVD, they just decided to release it for everyone now…. (?) So, the fact that it did nothing for me is not surprising… and it is unlikely that it fixed the wireless keyboard thing (though I am yet to try).
[...] Edit: Apple has updated Boot Camp with Vista 64 bit support, see here [...]