Power supply with battery backup

It would be nice to have a small power supply with built-in support for battery backup, including charging of the battery. I’ve seen the PC oriented ones, like PicoUPS (Google-it). While reasonably priced, these pack more power and size than what’s required for embedded projects. If it could take 12V in, and output 5V and 3.3V, I’d be that much happier.

Thanks!