I am an RFID system developer. Been in the business about 5 years.
I am not a fan of tagging people. Too many of the fears expressed here and elsewhere are indeed true.
We may not be able to track everyone everywhere or to read tags through walls TODAY, but just wait! Technology is moving very, very fast. And reading tags in hard to read places is a very, very important part of today's research.
Who would have thought "Echelon" for the Internet a few years ago. Who would have believed the USA government would be listening to your phone calls.
One does not have to have access to the "database" to track someone. I would suggest that a simple modification the the ubiquitous CCTV surveillance cameras popping up everywhere today could easily provide RFID "read" capability. Same infrastructure for moving data back to the monitoring point!
Simply seeing the same tag many times and in many places -- ie a Mall -- would provide you a good deal of useful information; such as which stores are frequented, what is purchased. If you are familiar with Web "tracking cookies" you know exactly what I mean...
