After the leaking of OSX many creative people attempted to get it to run on a normal PC. It seems they did it at hardmac.
There were 2 initial problem they had to cope with being: The TPM chip, SSE3 and the Intel GMA900 GPU. The TPM chip has been bypassed, the SSE3 instructions will be translated to SSE2 via a patch soon (this isn't needed if you have a SSE3 capable processor) and the GMA900 problem can be avoided by running a patch for coregraphics.
It seems the best hardware to run OSX on is an Intel 915, no RAID arrays (they will crash the system) and an USB keyboard since PS2 isn't supported that well.

For some additional info go to the source. Some videos are available here as well.