I'm a backups guy working exclusively with Tivoli Storage Manager from IBM since 1998.
Recently I've seen multiple large shops get the Virtualization Religion and virtualize everything without adequate consideration of each apps real requirements. They particularly hate it when I tell them that the TSM backup server has to be on physical hardware.

Mistakes I've seen are - VMing multiple SQL Server machines with one instance and a couple of databases each rather than running a big iron 3+1 cluster with multiple instances and more databases in each instance - and - virtualizing multiple Notes machines rather than running several Notes instances over a couple of real machines with app clusterimg.

In these cases the big iron will out perform the VM solution handsomely and with much the same availability. As always in IT you need to look at the pros and cons for each app separately rather than jumping on the latest bandwagon.