Note that a key advantage of WLAN-based techniques is that they are totally unrelated to GPS. GPS isn't required at all, nor is a clear view of the sky. We've toyed with the idea of using a combination of the two to provide world-coordinate-based location with accuracy of a few meters to indoor locations. This is done by establishing the location of a given AP with respect to GPS or other Earth coordinates, and then using a WLAN location technique to dereference off this point -- voila, real-world coordinates everywhere indoors, in real time.

WLAN location and tracking systems can be used for security, service discovery and location-based services. They also can be used to locate and track high-value people and things (like interns or defibrillators in a hospital) and to track shipping pallets in manufacturing and logistics operations.

A big question in front of us, however, has to do with the politics of such functionality. Might we be violating someone's privacy? Perhaps you saw Sprint Nextel Corp.'s announcement of its "Family Locator" service, which allows the location of a cell phone handset to be tracked and displayed, ideally, just to authorized users. While there are accuracy issues with the Sprint product, I expect them to be resolved faster than the political questions. But that's a topic for another day, along with the whole field of location-based services, which I'll cover in a future column.