One of the key concerns of those who are against RFID tags is the notion of "location privacy" where an identity is bound to some specific location thereby resulting in some weakness that leads to higher risk. There are a number of obvious examples where risk occurs when locations are known – particularly the whereabouts of public figures, armored car routes, etc. It doesn’t seem that far away where the world of "Minority Report" target advertising will be capitalizing on people-locations, though not through iris-scanning (I think this is what they did in the movie), but possibly through RFID tags.

But those worried about RFID tags have another more obvious candidate for these compromises: cell phones. I hope those activists worried about RFID are keeping their cell phones turned off because that risk exists today, and the compromise can occur from many miles away.