There is a lot of confusion among the early commenters. Some think this is a form of differential GPS, some think this is a network of WiFi devices, or a hybrid of WiFi and FM radio.
It appears to be none of the above.
It most likely is a pseudo-lite (a terrestrial device which mimics a satellite), except that it does not operate in the GPS (L1 or L2) band(s). The government, researchers, FAA and Air Force (which runs GPS) are working on real pseudolites which may run in the GPS bands. But this private company couldn't get rights to do that, so they are transmitting in 'the same band(s) used by WiFi. That is, they are broadcasting spread spectrum signals in the ISM band(s).
They apparently scatter a number of these, at highly precise locations, and a compatible user device would then listen to several and calculate its own position. Since their geometry is as flat as the nearby terrain, they will have very poor altitude accuracy, but because they don't have bending or delays in the atmosphere (or rather, those inaccuracies are trivial in comparison), they will likely have very good 2D accuracy.
Notice that things flying over the top of these devices would likely have good 3D (the geometry improves for them).
What is less clear is why this is preferable to using DGPS. DGPS is a 'station' at a known location which can measure the errors of each satellite (including bending/delay) and transmits corrections to nearby devices. DGPS is a government service in many areas, I believe, but can be set up as a private service, too.
The one real liability to the new Locata system, if I understand it (and I probably don't) is that they don't necessarily use GPS time. One of the really fabulous things about GPS is that it established a world-wide synchronous, highly accurate clock. In many applications that may not matter. It does for a lot of systems which rely on GPS time (too many to mention nowadays).
