From the article: "Location services company Navizon has a new system, called Navizon I.T.S., that could allow tracking of visitors in malls, museums, offices, factories, secured areas and just about any other indoor space. It could be used to examine patterns of foot traffic in retail spaces, assure that a museum is empty of visitors at closing time, or even to pinpoint the location of any individual registered with the system. But let's set all that aside for a minute while we freak out about the privacy implications.
Most of us leave Wi-Fi on by default, in part because our phones chastise us when we don't. (Triangulation by Wi-Fi hotspots is important for making location services more accurate.) But you probably didn't realize that, using proprietary new "nodes" from Navizon, any device with an active Wi-Fi radio can be seen by a system like Navizon's." Read more