All I know is what I read on Cult of Mac (Wired):
There was some debate a few weeks ago whether Intel Macs would boot Microsofts upcoming operating system, Vista, because of conflicting boot-up systems. While the Intel Macs use EFI, a new boot system from Intel, initial versions of Windows Vista will use the old BIOS system.
Well, in the comments to the blog post below, reader RLPM posted a link to a Flickr photoset showing his MacBook Pro booting off a Vista disk image, thanks to Apples new Boot Camp software.
RLPM says he didnt try a full install because he hasnt backed up his MacBook, and presumably doesnt want a disk error to wipe everything out.
He writes: After installing the firmware update and boot camp (didnt run boot camp assistant), it booted off the most recent Vista. I havent had time to backup my system, so I didnt install vista, but it boots from the latest image!
So I guess Apples Boot Camp software makes the whole BIOS/EFI firmware issue moot?