I've been fascinated by stories of self-organizing network of miniature sensors. IEEE Spectrum has a story about researchers who use a host of small devices called motes to do research on a bird colony in Maine. The motes are shaped like film canisters:

Each cylinder holds a bit of circuitry capable of simple computation and communication, plus a few environmental sensors, a battery, and an antenna. Taken alone, it's nothing special. But scatter around a dozen or a hundred or a thousand of these film-canister-sized cylinders--called motes--and switch them on, and something amazing happens: within seconds, they will organize themselves into a powerful yet stealthy data-gathering machine. Their quarry? A small and secretive seabird known as the Leach's storm petrel, whose comings and goings bird-watchers have long puzzled over but have never fully understood.

From Feature Article
Referenced Tue May 11 2004 09:46:15 GMT-0600

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Of course, the societal implications of these kinds of things are enormous. Right now, I expect that each on of these motes is both primitive and expensive. What is invariably true, however, is that within a decade Moore's law says you'll be able to buy a bag of 100 motes at Radio Shack for $25.

This is precisely the kind of things that David Brin was talking about in his book, The Transparent Society. Paraphrasing, what Brin suggests is that we probably won't get to choose whether or not these kinds of capabilities exist. Our only choice is whether everyone will have access to them or only the Government will have access to them. Its its the latter, things get pretty scary.