There is a nice article on Smart dust at FutureTAG wiki.
Small RFID modules (0,05x0,05 mm) have been "released" in 2007. In the future, Smart Dust could be as small as grains of sand. They could be used in a multitude of applications, ranging from tracking criminals or patients to detecting radiation or vibrations.
- Futures:RFID shows other tiny RFID devices
- Is "Rifidi - Software Defined RFID" relevant?