This article from IT Business Edge provides some virtualization do's and don'ts.

For example, in the "virtualization do" column:

The true benefits lie in management and productivity gains, allowing you to provision and deploy needed applications on virtual machines much more quickly than is possible in physical environments.

And on the "virtualization don't" side:

For many, virtualization has been a gift from the gods. But be careful not to hope for too much – you’ll only set yourself up for disappointment.

The full article is here.