The Guardian reports that Apple has won its suit against Pystar, the company that was manufacturing and selling clones running Mac OS on non-Apple hardware.
Apparently Pystar’s modifying the Mac OS bootloader was a significant issue in the ruling, weakening Pystar’s defense:
Psystar had claimed that “first sale doctrine” in the US means that the buyer (Psystar) can sell something on, regardless of whether the original owner (Apple) likes it. But the modification – “Psystar then replaced the Mac OS X ‘bootloader'”, to quote the finding of facts – means that first sale doctrine doesn’t apply any more.
According to the story, Pystar is already in Chapter 11 bankruptcy.
MacOS is built on FreeBSD, a Unix distribution. Unlike the GPL, the license under which Linux is distributed, the FreeBSD license allows FreeBSD to be modified and the modifications can be kept proprietary; that is, modifications can be released in binary form without release of the relevant source code.
The GPL requires that the source code for any modifications be released back to the community. (Release of source code is what “open source” means).