Recent NY Times piece about the use of cell phones and other wireless devices to track people movements and whereabouts:

""We are moving into a world where your location is going to be known at all times by some electronic device," said Larry Smarr, director of the California Institute for Telecommunications and Information Technology. "It's inevitable. So we should be talking about its consequences before it's too late."

Some of those consequences have not been spelled out. Will federal investigators be allowed to retrieve information on your recent whereabouts from a private service like uLocate, or your cellular carrier? Can the local Starbucks store send advertisements to your phone when it knows you are nearby, without your explicit permission?"