Most people don't virtualize, just for the sake of virtualization.
Usually, people go to virtualization, when they have an application/service that they want to make scalable, redundant, or static....or they have a specific "other" purpose.
Example 1....
I have a website.... I setup multiple virtual webservers in cluster configuration to give my site high availability and scalability.
Example 2....
I have a test bed of servers, whose configuration will always need to be the same, so that I can be sure i'm always testing against an identical environment when developing my application. I setup my servers as virtual servers, and everytime I shut them off, I can discard all changes.
Example 3....
I only have one server, but I need it to serve more than one purpose. I have determined that this server is not using it's full potential, so i'm going to install a virtualized email server on top of it to avoid having to buy another server.
