Apparently someone has managed to crack and load the x86 version of Mac OS X 10.4 Tiger onto VMWare, using a copy of the x86 developer kit dvd, a copy of Darwin x86, and some tweaks.
Info available at PearPC's website here: http://www.pearpc.net/
His site: http://xplodenet.com/
Screenshot of it running on VMWare is here.
It requires SSE3 to function completely, and it will work with limited function on SSE2 only cpus (no powerpc code
execution, iTunes, dvd).
As a result it will only run on newer Pentium 4s, as well as Athlon 64 and FX cpus.
Non SSE2/3 chips will fail to boot completely (Athlon XP, older Pentium 4, anything older).
I knew it was only a matter of time :/
EDIT: More screenshots (ALOT more) can be found here