As a hardware guy, id say a mini UPS to keep the pi up...ive already added a real time clock...maybe a next project for me ;)
Yeah I use quite a few UPS, although never for a Pi, but they are a hassle also, limited amount of run-time even with a rpi, so you have to have a way of shutting things down etc. I like the idea of writing the state, if it reboots, when it comes up it continues on its way...lots of ways to accomplish but would think you would want something that doesn't require a UPS.
