RFID (Radio Frequency ID) chips are slowly being rolled out and will eventually replace the bar-code. (Ever wondered what that little chip in your credit card was really for?)
Here’s a representation of how it will eventually affect your personal liberties.
For more information, I highly recommend the book “Spychips” by Katherine Albrecht.
Here are two patents to read if google’d:
Patent#20020165758: IBM – IDENTIFICATION AND TRACKING OF PERSONS USIN More..G RFID-TAGGED ITEMS.
Patent#6659344: NCR – AUTOMATED MONITORING OF ACTIVITY OF SHOPPERS IN A MARKET.