eWeek's Steven J. Vaughan-Nichols on the new Intel powered Macs:
For XP users, the problem is that Apple uses Intel's EFI (extensible firmware interface) rather than a BIOS. Windows, generally speaking, can't run on top of EFI....As for Linux, though, Intel has already provided a native Linux bootloader for EFI: ELILO (EFI Linux Boot Loader). With this you can boot Linux, even Linux that isn't EFI aware, without much trouble.
In his headline, Vaughan-Nichols calls this Linux Macintel.
Related: Dan Farber writes Running Windows on Intel Macs.