IT uses VMware Fusion for a few different things.
Often, we use it to run Windows on our Macs and in my experience, and for the most part, it's been pretty smooth. We use our Windows machine to access different servers, our domain controllers for example. We also use VMWare Fusion to run Windows machines for testing, so that we are able to test IT changes (for example, something with group policy) before pushing them out.
We also use WMWare Fusion to take snapshots as a basis for our Windows image that we use on all of our Windows machines. Other users in the company use VMware Fusion to run a Windows machine on a Mac, as well, so that they can install and use different financial software. We also have developers that use it to run quality assurance testing.