Virtualization is just amazing. It is just going to change everything in a very near future. Virtualization lets take possibilities beyond bare infrastructure and machines.
Whenever you see few computers in a lab, they are just connected in a simple LAN. These LANs are common in Labs, institutes, small companies, etc. Usually each computer in such LANs is an individual machine with some sort of file and resource sharing among all the machines and nothing more than that. Machines going down is not less than a nightmare for a Network Administrator or whoever is taking care of those machines.
In a very near future whenever you directly or indirectly use more than one machine, there are high chances that, you will be using Virtualization. Virtualization is used when you need a group of machines. A series of machines will just act as dumb terminals using Virtualization Server. If any terminal is down, no worries, just remove it and plug another one, and you are back, its just a dumb terminal, so no issues. All this is possible due to Virtualization. Virtualization can also be used in case you want a virtual machine in your physical machine. You can try out the things, play around the virtual machine in any way you want, that cannot be done with a physical machine :)