Coreboot is not a magic bullet. While it is open source, there are still likely to be bugs in specific implementations if an oem was to use it. Getting rid of the bios is also not exactly a good option either. With no bios, you lack a standard way to boot the system and you end up with a mess like linux arm currently is (tons and tons of system-specific configurations that make booting a generic kernel almost impossible). Also, for things like ASPM, they have to be validated on the platform. If the OS doesn't support it (IIRC, XP did not), the different combinations of hw were not likely to be validated so they may not work in practice.
No announcement yet.
The Leading Cause Of The Recent Linux Kernel Power Problems