I wonder if this could be used to track objects in a room as they move about, perhaps providing better resolution than GPS? Also, I would like to point out that one of the items on his list was a `cat`.
To get location information would require one of the following: 1) An array of antennas pointing in different directions, this is certainly possible, but not using the single built in antenna in a smartphone.
2) The device to know its own location and to transmit this to the phone. This would only be as accurate as GPS and would use significantly more power.
Using signal strength to approximate distance is reasonable, but the location of the sensor, nearby objects and the design of the phone's antenna will all affect the measurements.