I would just like to point out that when done properly, virtualization adds in a layer of safety. Because, assuming you run the same virtual machine software, the operating system sees the same hardware every time, regardless of what the physical hardware actually is. So, as long as you keep backups, if your main server with everything on it goes down, and it's virtualized, you can just pop the VMDK file or whatever into another physical server's VMWare program, and be back up and running in the time it takes to copy the file. This is great if you have a hot spare lying around. Then, once you get your main server back up and running (or replaced, whatever), you can just throw the VMDK file back into that, and be running, again.

Virtualization does more than just consolidate hardware, people. It wouldn't have taken off quite as much as it did if that's what its whole purpose was.