Radio-frequency I.D. (RFID) tags are a convenient way to track items and cut costs for companies. But this technology is increasingly being used to track other things, like security badges — or even people — giving it the potential to cause a horrific erosion of privacy. Tracking people with smart tags, their shopping preferences, their activities, and their personal belongings sounds like something from a sci-fi thriller. But If you got your panties in a twist over Walmart's decision to track your undies via RFID smart tags, then you'll be doublely concerned at how close we are to cradle-to-grave surveillance.

RFID tags reached a tipping point with Walmart's announcement that, starting next month, the retailer will place removable "smart tags" on consumer goods. The RFID tags can be read by hand-held scanners to track inventory levels and keep a better eye on loss prevention. Recent drops in the cost per RFID tags have encouraged adoption of this technology. With Wal-Mart publicly embracing RFID, you'll see other retailers quickly fall in line.

If your trash is filled with RFID tags, your trash could be exploited by cybercriminals (driving by with a RFID reader). Perhaps consumers should be advised to trash the offending tag before they leave Walmart parking lot? I’m honestly less concerned that cybercriminals will be cataloging an individual’s purchases via their trash than I am about RFID becoming "spychips" — using the RFID technology to track the whereabouts of citizens who have no idea they are being tracked. RFID chips are already embedded into passports and other everyday items. These potential-privacy-decimating spychips can be the size of a dust speck...