Not to be blasphemous, but in looking at alternatives, don't forget Haiku (BeOS).
If you look at how AmigaOS was intended to go to a more object oriented design, Haiku starts looking pretty similar and it runs on both x86 and PPC with an ARM port in progress.
Like AOS it has a highly responsive UI, good multimedia capabilities, heavily threaded plus memory protection, AGP, PCI, PCI-e, USB, WiFi in progress, quite a few existing apps...
Many of the things we're trying to shoe-horn into the AOS3-like OS's are already there.
I dare say that had AmigaOS continued development, it would have had little more resemblance to AOS3.1 than BeOS does.
Edit: I forgot that Translators are pretty much a direct rip off of Datatypes.
