REALLY good question - I'm glad you asked. The question isn't really SHOULD you anymore, however under what circumstances should you virtualize. Microsoft has released some great guidance as to why and under what circumstances virtualization is a good idea and under some circumstances why it should be actively encouraged.
4 Scenarios are discussed which include:
The technical checklists at the end of the article are of great value as well, even if you're not considering any kind of virtual hardware but want to deploy physical hardware instead. Remember that you should never virtualize a workload on physical hardware that's not up to the task, and while I hear you say "DUH", I see it more often than not.....