A good reminder and for the ones who are too deep into the complexity of it (me included), "See virtualization as your next-level strategy vehicle". That it!
While virtualization brings very powerful offerings to the datacenter and to IT professionals worldwide, it also has inherent issues. All VM's are stored within folders and files on their host machines, and because of this, it's really easy to provision and proliferate VM's. For instance, a user would take machine number one's files and copy them to create machine number two, repeat to create machine number three, repeat again for number four and so on.
However, all machines - even virtual ones - need to be managed. It's true that companies save on hardware management, but IT administrators still need to manage the OS, update it, secure it, deploy software to it and perform other general administration tasks on it. And in addition, there is now an additional, virtualized layer to manage.