Yesterday a coworker passed me a link about an OpenGL virtualization project from GSoC '06, VMGL. Basically it allows you to show OpenGL accelerated graphics of applications running in a virtualized guest OS like Linux.
The results of the benchmarks are just impressive. Almost native performance and concurrent execution of various games like Quake3 or Unreal. It's been tested with Xen and VMware as far as I have read. Further work to achieve the same features with Direct3D is planned. Meanwhile, guys on VMWare, are making amazing things like this.
I'm starting to seriously believe that this kind of progress on the virtualization space is going to change we think about applications, operating systems and even debugging. The boundaries of the platform where you run your applications are just going to be blurred, and users, developers and customers, are going to be able to have real choice.