This Guardian story mentions in passing:
Not only can operators pinpoint users to within yards of their location by "triangulating" the signals from three base stations, but - according to a report in the Financial Times - the operators (under instructions from the authorities) can remotely install software onto a handset to activate the microphone even when the user is not making a call. Who needs an ID card when they can do that already?
The infinity transmitter comes to the cellular age. Hmm. I wonder how much soundproofing the way my Samsung flip-phone covers the microphone when the phone is closed gives?