Well, I finally got around to completing the first stages of my experimentation with Xen for eventually moving all my server stuff into virtual machines.
I’ve got my Subversion + Trac server running in a Xen VM, on a Linux box in my garage. It’s working fine for now, but eventually I want to move my server hosting account to a dedicated (or colo) server instead of a VPS and then run my Xen VMs there instead of at home (although running it here also has its advantages). I’ve also thought about trying running Xen under my current VPS plan, effectively running VMs within a VM, but that might be stretching it in terms of performance.
The great thing about this is that you can isolate your servers into individual virtual machines which you can easily backup and move, etc. and also allows them to be more secure, since a compromise in one would only expose the limited scope of that sub-server, rather than your actual server or any of the other services you’re running.