You're right. Maybe it's not as easy as I made it seem there. It's definitely possible, if you think of VMware's vMotion (live migration). That implies a shared hypervisor _by VMware_, of course, ... but it shows that technology-wise it's doable. When I saw vMotion for the first time, it blew my mind. Now all I can think of is how cool it would be to have that among different devices (laptop->desktop->smartphone->..).
vMotion is cool, but it works on isolated VMs, which is an easier job than migrating an application running on a desktop and integrated with the rest of the system (unless you completely isolate all applications like on the mobile OSs, but then you lose other things).
