It seems unlikely that MS won't have certified drivers for BR drives in Vista since there's already documentation and even a quote from an MS rep stating that they plan to add auto-play support for BR drives in Vista- just not native movie playback.
"In short, Windows Vista will support (i.e. recognize) Blu-Ray discs, but will not natively support Blu-Ray movie playback; for that, you'll still need third party software."
I don't think MS would waste the time to add auto-play features for BR discs to Vista if they didn't plan to certify software drivers for the drives.
We won't know for sure for a while now- especially now that Vista may
be getting pushed back even further than Jan. of '07.
What I do
know, putting the BR/HD-DVD debate aside for a brief moment, is that the UAC scheme is an absolute joke right now- and it had better improve greatly before RTM. It's actually more intrusive and disruptive than the UAC in OSX, and I didn't think that was possible. I've never felt like as much of a spectator when logged in under an admin account as I have with the most recent couple builds of Vista.