I've recently begun playing a lot with tiny programmable computers/controllers (like the Raspberry Pi and the Arduino), and I'm planning to distribute several throughout my house as various sensors. So far as I have been tinkering with them I've been using a wall-wart transformer with a USB plug to provide them with 5v (like the one I use to charge my cellphone every night). The problem with doing this throughout my house is that I do not have an AC plug wherever I would need a device.
I've been thinking about running a 12v "bus" throughout my attic, which would allow me to branch off power for devices wherever I need it. This way I would just need a 5v regulator to pair with each of the devices. (The only reason I would run 12v and not straight 5v is because I already have a large 15-amp 12v switching power supply which I could use)
Is there anything special I should consider with this solution? I feel much safer running 12v around in my attic than I would running my own mains power lines. Seems like a no-brainer on the surface, but I may be overlooking something.