Perhaps I'm missing the point. If one is going to boot up between OS's that often wouldn't virtualization work best? Other than that it is a neat hack.
edit: grammar
See page 7. of this document: http://www.vmware.com/pdf/asplos235_adams.pdf
2 Gaming Rigs, 1 Tower - Virtualized Gaming Build Log https://www.youtube.com/watch?v=LuJYMCbIbPk
7 Gamers 1 CPU is back! But does it ACTUALLY work!? https://www.youtube.com/watch?v=opX-AsJ5Uy8