It is the first week of January, and forecasts here in Boston call for highs of almost 60^oF. In the throes of unseasonable spring fever, and with the convenience of snow-free streets, it is not easy to muster sympathy for polar bears laboring under the hardships of global warming. I know, however, that their discomfort on the northern fringes of the continent signifies a larger encroaching problem--one that may someday affect me. What prompts me to spare a thought for those creatures in the distant north is a question about RFID (Radio-Frequency Identification), a broad term for wireless microchips. During a recent discussion about the convenient RFID (tap-and-go) transit cards recently introduced in the Boston area, a colleague of my wife asked why I care about RFID privacy so much. He added, "I don't. I've got nothing to hide."...