Mac developers at WWDC had expressed concern that the current x86 demo machines sport a standard PC BIOS, and doesn't support basic Mac features like Firewire booting. Current Macs use Open Firmware but Apple has already said that it is abandoning it in its new x86 machines, but hasn't officially said what it will adopt. Perhaps to ease those concerns, Apple appears to be hinting that it will adopt EFI:
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.Just like Apple's iMac gave the USB standard the boost it needed, Apple's x86 Macs may turn out to be the kickstart for EFI, too.
The general consensus I've heard from other developers is:
1) They don't want us to use BIOS
2) If they haven't heard of EFI, they want us to use OF
3) If they have heard of EFI, they want us to use EFI
This is not a statement about what Apple will use, just what I've heard from developers that have an opinion on the subject.