Century City was a lawyer drama set in the future which tried to look at future legal situations (think cloning, meddling with embryos to produce the "perfect" child, etc). Only eight episodes were produced in 2004 and four were never aired (including the one I'm thinking of; though they are (were) obtainable via p2p). One episode (Without a Tracer dealt with a possible result of this sort of device.
Basically, every child has a tracer (linked to video/audio surveillance no less). The episode revolves around a teenage girl who was fed up with being watched by her parents and removed her tracer, at which point the parents panicked because she'd apparently vanished. IIRC she hired a lawyer to get a ruling to "allow" her NOT to wear the tracer.
Their point was that this sort of device, whilst well-meaning, can become intrusive. I think (and the drama hints) that the tendency will be to rely on devices, further abdicating parental responsibility. Furthermore, I wonder if anyone's considered whether this would make the wearer EASIER to target, should the ID for their device become available, e.g. to someone wishing to kidnap a child for extortion.