That would be a neat trick. I guess it could be possible to work on grub to do that but no, it doesn't offer quite that much. grub is a boot loader for real installs. Throwing an emulator or ability to read a vm virtual filesystem into it is a bit of a trick.
Grub or at least grub4dos or grub24dos or such might be able to boot to a live cd if you set it all up correctly and a few other variables are OK.
It would be possible to convert your vm to a raw image and maybe boot it.
Last edited by jefro; 12-28-2011 at 07:00 PM.