Both, MorphOS and AmigaOS4, are also running on PPC-equipped Commodore Amigas, but neither of them are publicly available, just for developers / betatesters.
Bill Buck is the CEO of Genesi, a company combining him and his wife with bplan, the company which developed the Pegasos mainboard (PegasosPPC.com). Also a member of bplan is Ralph Schmidt, main developer of MorphOS (MorphOS.net).
Saying MorphOS would be a splinter group is a dangerous statement here and could start another flame war. The opinions differ. Indeed AmigaOS4 has the official licence, i.e. it uses the name Amiga and the AmigaOS 3.1 sources could be used for its development.
On the other hand, as has been already mentioned here, MorphOS started earlier, at a time AmigaOS had officially been declared dead by those who acquired Amiga from Gateway and were running the current Amiga Inc. Also, bplan consists of ex-employees of phase 5, which you do certainly still remember, especially from the PPC-boards for Commodore Amigas you mentioned. The graphics system of MorphOS is CyberGFX, Frank Mariak actually is part of the MorphOS team. Another integral part of MorphOS is MUI from Stefan Stuntz. So one can certainly say that MorphOS also does incorporate much of Amiga spirit.
Therefore, it's up to each user individually which of both efforts he considers the most legitimate and which the "splinter". After all, I'd always recommend to simply visit a local Amiga show and compare both systems oneself - some people the one suits more, some the other.
After all, both have the same roots, the users of both do basically like the same features, i.e. simply the Amiga way of computing, and therefore we shouldn't be hostile towards each other, IMHO, but rather stay the friends we've been before and just enjoy our common hobby and memories of the good, old 80s and early 90s.
