Apple has not commented on the upstart - and it may not have to. It can always sabotage the usurper by issuing updates that won't run on the alien machine, or that disable it. Apple has done that with iPhones that users have hacked to run on wireless carriers other than Apple's chosen, AT&T.
Most users install operating system updates automatically by downloading them over the Internet, so this could be a no-brainer for Apple. Of course, Psystar could issue a patch to counter Apple's patch, and Apple could issue a counter-counter patch in its next release, but that's not much fun for users.
The saving grace for buyers who want to experiment is that this Mac "clone" can be transformed into a real Windows machine by slipping a Windows CD in the drive. So you have to bet only the cost of a new operating system, which is unlikely to affect anyone's retirement. To paraphrase an old John Updike essay, the OpenPC is progress with an escape hatch.
