Mac OS X running on "any" PC.
Well, not any
PC, really, but more than just Apple's transition kits. MacBidouille has the info in french
, along with two movie files showing the PC booting quickly into Mac OS X. (The video files are currently not available, it seems. Probably, the servers are under heavy load...)
According to the article, the DRM module's protection can be avoided quite simply (using a patch). So, for those who're willing to illegally download a copy of Mac OS X for intel Macs and are willing to illegally circumvent the installation protection doing some handiwork, it's possible. At least if you're running a recent intel board with the right graphics chip and a P4 that supports SSE3.