Storage virtualization comes in many different varieties. You can virtualize by block storage, or on the file level. You can virtualize just your disk drives and other devices, or you can opt for a virtual tape library. Heck, a storage.itworld.com article says the "Save As" button in Word is a form of virtualization because it interfaces to the OS file system that takes care of many of the mundane storage tasks that once had to be done by hand.
It's tempting to glom onto virtualization as the key to all your storage woes. Capacity will improve because you won't have to over-provision anymore. Management becomes easier because you no longer have to track exactly where and how specific data sets are being handled.
As in most things, however, moderation is the key here.
It would be great if you could have a fully virtualized storage environment in which location, media type and file formats became irrelevent, but we're not there yet. Interoperability, particularly in multi-vendor environments, is probably going to be a continuing problem. And then there is the old phrase about biting off more than you can chew, which is probably more appropriate than usual considering that this is bleeding-edge technology that is largely unproven in the real world.
Suffice it to say that the best strategy at this point is to keep it small, say, on a single array, using only one manufacturer's technology. Once you get your feet wet, you can always take the plunge later.