Indeed an interesting field, it's usually the manufacturers of chips for embedded systems that produce evaluation boards to show their products off / give a development platform. Sooo, I'd goto the various maufacturer's websites and look for them there, I know RS (http://rswww.com
) sell various eval boards and embedded PC boards...
Hope this helps!
Motorola manufacture PowerPC chips, and a standard PPC kernel *should* work.