At last night's New York MySQL Meetup we had a great presentation on the new stuff in RedHat Enterprise Linux 5 from Goutham Kandiar (from RH's NY office down the block). The highlight was when he moved a running MySQL server from one laptop to another.
Now, I'm a Sales Engineer, so I can appreciate good dog & pony shows. I can really appreciate the difficulty of making a dog or pony of a database. So this was quite a treat.
It turns out all you need is some reasonably modern hardware (they had Lenovo T60s with on-chip virtualization) and xen. You can use older hardware, but you'll have to modify your kernel (which limits you to OSes where that is a possibility). Goutham had a gigabit switch, making the 256M image move over in ~4 seconds, but he told me that an ad-hoc 802.11g network would still do the trick in about half a minute.