jmichaelg writes "What do you get when you combine a glass, a PIC computer, two capacitors, a coil and a zener Diode? A wireless beer glass that signals your waiter when you need a refill. The circuit is an RFID transponder that measures the fluid level in a glass and transmits a globally unique ID coupled to the fluid level reading when queried by an antenna hidden in your table. The query provides enough power to drive the circuit so no batteries are needed. A technical paper describes the circuitry in the table and the glass." This hit the news over a year ago, but we didn't have the technical details.