In terms of advantages, RFID tags provide a level of granularity in tracking items that hasn't been economically feasible before. The tags are revolutionizing inventory management, and that's a good thing. From a security standpoint, it's possible to use tags to track assets, which could provide more control over where employees take company-owned devices, but that assumes there are RFID readers everywhere an employee would be.
There are also physical security use cases of RFID tags. For example, they could replace the well-worn proximity card readers that most buildings employ. I'm not sure of the economic benefits, but it's certainly a possible use case.
RFID implants have similar application security requirements as tags, but the privacy issues are a totally different ballgame. If medical records are linked to the RFID implant, there are serious HIPAA mandates to protect that information.
As the technology evolves, I believe that human RFID implants could become a slippery slope toward a Big Brother environment. Right now, to my knowledge, there are no GPS-enabled RFID implants -- at least of the variety that could be tracked anywhere in the world -- but eventually they will become reality. Then the question becomes more about ethics than security.
This was first published in June 2008