There's something that people talking about OS4 on the PS3 are overlooking - and that is that Sony has completely locked you out of the hypervisor unless you give them a lot of money. Case in point, there was a rolling homebrew demo showing off some blitter operations, well, guess what? The hole that the coders used to do it was closed up by Sony in the following system update.
Ain't gonna be Amiga OS on the Playstation (unless you're running UAE through Linux).