CherryOS is a fully-functional Mac OS X hardware emulator for the PC. You’ll still need a copy of Mac OS X, but apparently it otherwise works just fine – at least until Apple brings in the lawyers. I don’t have any hardware to tinker with this on, but sure would love to check it out.
However, the website makes reference to “pre-orders,” so it remains vaporware for now. My understanding is that the site has been hammered since they did some press, and that has prevented me from more thoroughly exploring the site.
Hmm. On further investigation, pinging “cherryos.com” returns “unknown host,” at least from here. Maybe the lawyers are already up and at ’em. A WHOIS records an active record for the site, and the listed nameservers are both up, so I assume they are just down at the moment.