I was watching the Science Channel and they had a snippet on "Smartdust" and were talking about how building could have these small sensors on them to help them communicate with other buildings, devices, etc. Really the devices could be used to communicate with any other devices embedded with them. As defined by Wikipedia:
Smartdust is a hypothetical network of tiny wireless microelectromechanical systems (MEMS) sensors, robots, or devices, installed with wireless communications, that can detect (for example) light, temperature, or vibration.
Tons of cool info on this, and just thought I would mention it in case you had not heard of it.
‘Smart dust’ to explore planets
By Paul Rincon
Science reporter, BBC News, Preston