(Click on the pic to watch the video)
Basically, these two dudes have installed Linux and a virtualizer on a PC in order to have a virtual machine running MacOSX. The trick is possible thanks to assigning devices to the virtual machine, so there are two GPUs installed and one is completely dedicated to MacOSX so the user experience doesn't suffer any lag.
Well done! I am just thinking about using Premiere or FinalCut in the virtualized MacOSX and comparing its performance with a mac.