It has been a while since Tempest has come up here. If you haven't heard Joel McNamara's is closing his unique web site on TEMPEST in October, 2011. An archival pdf is available until then: http://eskimo.com/~joelm/tempest.html A lot secret and open research is still underway on compromising emanations and inadvertent signals of humand innards, outwards and behavior -- electonic, acoustic, visual, odor, taste, touch, multi-sensory, extrasensory, paranormal, stride, eye blink, arm swing, bodily excretions, crowding, solitude, sleep, grammar, syntax, singing, math and coding skill, down the line of reading what you don't want read without getting bitcoins in return. Much of Tempest discussion focuses on electronic emanations but are there reports on non-electronic signal capture? The report recently on big cavity resonators in Britain built before radar to pick-up acoustics of distant aircraft reminds of the non-electronic versions of Tempest popularized by the KGB's planting a device in the US Embassy residence in Moscow. Passive bugs are not the question. Are dumb-looking objects still being covertly planted in secure locations to transmit signals to the outside at imperceptible wave lengths or stego-ed in the perceptible? Bypassing cutting-edge Tempest countermeasures which so enthrall technical surveillance inspectors blinded by e-gadgetry. Are live skulls cavity resonators beyond pushing voice? Lot of cavities in most places where people go for privacy.