Yes, OS 4 is PowerPC only. Certain invidiuals might be tempted now to jump in and tell you that is being developed on Amitlon (untrue). I just read somewhere else that it had been running on 68k before (untrue). Fact is it is PPC only. ExecSG has never existed as 68k.
It was a matter of perspective really. Maintaining two separate code bases for 68k and PowerPC would be too much of a hassle. Apple's budget is definately a bit larger than ours.
Besides, AmigaOS 4 needs an MMU. To the best of my knowledge neither UAE nor Amithlon nor AmigaOS XL supports an MMU. This has nothing to do with virual memory (as in swapping to disk), which can be disabled, but rather because of the virtualized memory architecture. This rules out emulated systems.
