Virtualization is becoming more prevalent in the enterprise (if not the standard for many places). How does one virtualize OS X and at what cost you may ask? You can do it for free, believe it or not, using ESXi. ESXi officially supports Mac Pros (the “newest” revision) and unofficially works on Mac Minis.
Rich Trouton recently explored settings up ESXi on a 2011 Mac Mini and wrote up his experience here. It is well worth checking out if you would like to virtualize OS X. Rich was also kind enough to document how one might use VMware Fusion along with several common OS X deployment tools in another post.