I was just browsing through articles when I happened to find this one. In this video of TED, Todd Humphreys talks about the near-future of geolocation when millimeter-accurate GPS "dots" will enable you to find pin-point locations, index-search your physical possessions ... or to track people without their knowledge. He also talks about a GPS spoofer he made, and if it is fallen into the wrong hands... the results could be catastrophic.