Boosting graphics performance in virtual machines

A hypothetical question:

I read somewhere that the MacBook Pros have Intel integrated graphics (disabled) as well as the discrete ATI graphics. Would it be possible for a virtual machine to use the ATI graphics while the host machine uses the integrated graphics? My guess is that this is something only Apple can manage. But is this theoretically possible?

Also, with the future Intel PowerMacs, would you be able to add a second graphics card that the virtual machine could directly access?