Intel delivers all of their boot support code as EFI drivers these days.
But not as open source. Tiano is a huge bunch of code, but the really interesting bits aren't in there.
EFI is much better than BIOS. It runs in full 32/64 bit mode.
coreboot welcomes you to 1999. Besides that: why is it that EFI exists in "either 32 or 64bit", instead of cleanly supporting both? The additional complexity of thunking libraries can't be it, as tiano already provides a runtime loader to resolve in-flash libraries...
Booting Intel machines is really fucking complicated, and EFI makes it much simpler.
Sorry, but EFI is fucking complicated, too. runtime linker - I rest my case.
It's just that you don't have to care about this complexity when intel provides the closed source components to you to plug in.
The most reasonable action about EFI over the last few years was the EFI shell effort. Finally Intel admits that they designed an operating system instead of a hardware bringup.