Engineers in Britain have developed a super-miniaturised mobile phone that can be
implanted in a tooth. The phone receives digital radio signals and transmits them to the inner ear by bone resonance, in a way that no-one else can hear; it can be implanted during routine dental surgery.
No word on whether it contains any sort of microphone or means of sending sound.
(How much do you want to bet that the CIA/MI6/&c. have already had something of this sort for some time?)
(via Techdirt)
re : mobile phones in teeth. There were whole slabs of scenes cut out of "Hedwig And The Angry Inch" (look it up on IMDB.com) of the band's manager with a tooth phone. It was visual comedy that didn't fit at all with the film. Lots of taping teeth with her tounge to answer and tapping again to hang up, talking stupidly into space... nobody wants to look that stupid?