For the past few months we have been running multiple labs, two physical blades each, to do development against the vCloud 5.1 Beta. With the capacity that we have available in our overall lab, a nested approach like the VMworld labs would be a nice fit for our development team. Ideally we could spin up full vCloud instances in minutes. My experience thus far with nested environments was running vSphere in workstation to study for my VCP exam.