Mordechai Guri of Ben-Gurion University of the Negev in Israel has found a new way to covertly extract data from air-gapped computers. It's limited (at present) to a bandwidth of about 50 bits per second, and its range is only a few metres, and it can be defeated by background noise, but the concept of a "singing capacitor" is a fairly lovely one 🙂
"Where does this leave air gaps as a concept?
The US Defense Advanced Research Projects Agency (DARPA) is now concerned enough about the attacks to fund research into how computer isolation could be re-thought."
I think vacuum-gaps are the next step ...