It wasn't working very well on an older Toshiba laptop, so I held my breath and took the plunge into Windows Vista Build 5219 (the one handed out at the PDC) on my IBM ThinkPad T41p. It has an ATI FireGL T2 video card in it, fully supported by the LDDM. In fact, I got glass effects from a basic install without needing to upgrade any video drivers. Kinda.
It seems I'm running the latest ATI drivers for Vista, but I can't maneuver my screen resolution past 800×600! Annoying, to say the least. I've been scouring forums and message boards for a workaround / tweak, but it seems that I may have to put up with a lower resolution just so I can get all those fancy glass effects (which, admittedly, are less annoying than one would think them to be). I'm not ready to remove my rose-tinted glasses yet.