Hi,
I've got Vista Ultimate installed on my MBP in my sig. I did an upgrade from XP Pro. Install went surprisingly well for Windows
though it did take a while I thought. The iSight doesn't work...yet and the tools that Apple provided for mapping the keys, eject, brightness control etc, don't work either, but thats only a minor niggle. MacDrive is also a no go. I don't think its Vista compatible yet. Also I had to reinstall the sound driver from the Boot Camp CD once I had Vista installed.
Remember that Vista has to be installed on the NTFS filesystem so you cannot write to the Vista partition from within OSX. I actually like Vista. The interface is very nice, I think. Such a huge improvement over Fisher-Price XP.
[EDIT] Apparently Mediafour who make MacDrive are working on a Vista-compatible version and should release an update once the official launch date for Vista has passed. Sometime around Jan 30. 2007 then.