Just recently, I've had to move the system databases to a drive separate from the user databases due to a requirement from a 3rd party tool. We are evaluating using the backup process that our SAN vendor provides. That tool requires that the system databases be on their own SAN drive in order for the tool to work.
It was interesting running through the process. I learned a lot that I wasn't necessarily planning on learning, specially in the test environment. :-) For example how to recover SQL when I didn't do things in the right order, or got too click happy, or fat fingered something.