at my 250k employee company with a bajillion servers and workstations, virtualization is mostly a work-around for the ancient and technophobic company policy of seperating servers by the individual application they run. All of my department's server side stuff (except the database) can easily be run on one box with one active/active failover box in a different location. This is how it was demo'd, benchmarked, vetted, and tested. Corporate audit went ape shit that we had an APPLICATION SERVER that was also SERVING UP WEB CONTENT!!!!!!!!! Fast forward 8 years and we have THIRTY TWO virtual servers in EACH ENVIRONMENT (production and fail-over). All doing the job of one decent server, and realistically all together taking up one server's worth of hardware (but with much more OS overhead BS than just using the one stupid server for the various applications.
So basically we pay some VMWare licenses, 62 extra windows licenses, some hefty maintenence contracts, and who knows what else in order to use the server in the way that the software originally was intended to run (1 box for all the apps). Nice workaround for braindead company policy.
Honestly, other heavily virtualized shops that I have seen were mostly the same thing.
Virtualization in the business world is really just a work around for the fact that computers got more powerful faster than they were able to gain trust and confidence of senior management.