(P.S. I know someone's going to mention AROS, but no. Whatever its other merits, it has exactly one 68k port, which is deprecated and not even for the Amiga, and one PPC port, which seems to require an existing Linux install. It might be an Amiga-inspired or Amiga-based operating system, but it's not an Amiga operating system.)
FYI, it has a native non-Linux hosted x86 port and in the last couple of weeks, the native 68k Amiga port has finally been revived and is making serious steps forward.
The first bounty was assigned and has a delivery date of around December if I remember correctly.
I'd expect a usable native 68k Aros in the next 6 months to a year if they keep this pace.