First of all, the 68k emulation in OS4:
Yes, this is a JIT-68k emulator. It's called "Petunia" and is not based on the UAE-JIT patch. Why? UAE-JIT is for x86 processors. Porting a JIT emulator to another CPU is next to impossible (no sane person would try to do that). Apart from that UAE-JIT is GPL. The OS4 68k-emu is part of exec.library (AmigaOS' kernel), so that would have to become GPL'ed too. AmigaOS is proprietary software, guess how much the idea of open-sourcing the kernel appeals to Amiga Inc?
The JIT emulator is tightly integrated into the OS. It's only purpose is to run software that is not PPC native yet. It's absolutely useless for retro-gaming. An Amiga port of UAE exists, but this is some very old version.
Next: support for PowerMacs.
This is a bit complicated. Hyperion really want to support PowerMacs - simply because that would give access to pretty decent laptops.
The problem is Amiga Inc.'s licensing scheme. I can't comment the probability of a PowerMac OS4 version (not yet), but the main problem is this:
OS4 will require the presence of a hardware dongle. With the AmigaOne, this dongle is already part of the standard ROM. With other machines (such as the Pegasos or PowerMacs) other solutions would have to be used. An example would be an USB dongle.
Additionally, somebody has to step up and sell OS4 for Powermacs or Mac/OS4 combinations and provide support for end users
. This seems to be pretty important to Amiga Inc. - anmd that's good IMHO, we all remember Commodore's customer support.
There are other issues, but these are the main problems.
Somebody used the term "overpriced". I don't think an AmigaOne will be more expensive than a similarly specced Mac. And A1s are produced in extremely low quantities (even compared to Macs). If anything is overpriced, it's the Mac