Layman's Logic has a brief summary of some of the issues surrounding RFID tags (radio transmitters in products), which soon may be in most goods in large stores. One issue is quite how kooky a number of the opponents of the tags are. Another is persistent rumours Euro bills with have tags in in the future. Another is what to do about them:

"[W]hat I need to know is how to kill the tags when I get them. I don't care that people can see what I'm buying when I use cards - they can see that anyway if they can access credit info, and they want to track stock. Not a problem. On the other hand, I would like to know how to kill the tags the moment I've bought something to avoid any nasty privacy surprises. Fortunately, Slashdot seem to have identified a few possibilities"