I'm about to set up a location with a bunch of mini-ITX Atom mainboards that run on a single 12V input, so there's no need for a UPS. They're also very efficient (each board draws less than 20W) so even a medium sized battery will provide for at least a few hours runtime in the event of a total power loss. I'm looking forward to putting it all together.
If you're really keen you can get a gas powered backup generator like PersianKitty... it will keep more than your laptop running.
