Erich Styger has been working on a UPS with the Raspberry Pi to cover a short power out:
There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:
1.Excessive writes to the SD card can wear it out
2.Sudden power failure during a SD card write can corrupt the file system
For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.
Project info on MCU on Eclipse site.