> None of the Amiga-like OS fully supports Power Architecture. MorphOS
> usually does, except for the systems which contain more than one core.

Power Architecture is an ISA, not a chip or system. Therefore it makes no sense claiming an OS doesn't fully support Power Architecture just because it is a single-core OS. After all, the ISA allows for single-core implementations, of course. A single-core OS can't fully support a multi-core chip or system, but the ISA is per core.

> Are there many (and current) Power Architecture systems containing more
> than one processor core?

Yes, there are hundreds of systems using more than one core that complies with Power Architecture currently on the market from a broad range of vendors. They are mostly specialized systems for embedded, networking, telco, industrial, imaging, storage, military etc. use.