I'd think that you'd need Apple's permission to run Mac OS on an A1, not AOS on a Mac. My Mac G4 already runs all the PPC linux distros, BSD distros, Mac OSX and Classic 8.x/9.x so it must not be very hard to get something else running on it. ?? I bet this one will be a good seller for Apple.
Afaik Be inc had to stop mac/ppc developements of beos, because of lack of support from apples side.