One dev mailing list post leaves the BIOS/Firmware question for upcoming Intel-Macs open:
We realize there are lots of folks that need to know what is going to be in the ROMs on these new machines, and what partition scheme will be used. Unfortunately, we are not yet in a position to make that information available, but we will communicate it as soon as we reasonably can. Don't assume that what you see in the transition boxes represents what will be present in the final product.