A pair of MIT engineers are working on a real world Cone of Silence like the one in both the new Get Smart movie and the '60s television series of the same name — though hopefully the duo's take on it will be more successfully then the often faulty fictional Cone.
Ditching the idea of plastic domes or enveloping forcefields, Joe Paradiso and Yasuhiro Ono are instead looking into a network of sensors that could identify possible eavesdroppers. The system would take quite a bit of rigging as a room would have to be equipped with a bevvy of sensor units that house a microphone, speaker, infrared sensor and a network card to connect to a server. Then, if someone wants to chat discreetly, they'd just activate the "sound shield" from their computer, and the sensors would locate anyone not in the immediate vicinity and wash out the conversation with some white noise.
MIT's system has the advantage of being able to track people who could be listening and continue to drown out distant conversations with an ambient buzz. The real test, however, will come when it comes time to discuss pricing and ease of installation.