And it's increasingly looking like the main architectural difference between the new Intel-based Macs and, say, Dells or Sony Vaios, could be the key in the DRM chip which authenticates it as an Apple, allowing MacOS X to run on it.
I take your point about the bytecode, though isn't it owned and licensed by Intel, who have a vested interest in their own architectures? As such, wouldn't EFI becoming a de facto standard in OpenFirmware's place freeze out the likes of SPARC and (what remains of) PowerPC?
I doubt it. At the worst, other architectures will continue to use other boot methods, and all the x86 world will change over to EFI. Big win for x86 hardware/OS people, no change for the rest. Apple have shown that switching architectures doesn't preclude changing boot code - in fact, apart from the TPM, I think it makes very little difference.
In what way is EFI proprietary and architecture specific? It looks pretty open to me, as well as being architecture agnostic; there's a bytecode interpreter built into it for writing portable device drivers/POST routines.