Marc Orchant got the Vista install disk working with a MacBook Pro and Boot Camp. What was his secret? Well, he just inserted a Vista disk instead of a Windows XP disk. There are also reports that Boot Camp supports various distros of Linux.
Update: Well, it looks like the Vista install process works, but Vista itself? Not so much. So, you can install Vista on an Intel Mac but you just can't run it.. much like a PC. I kid, I kid.