An important note on the 69-foot record in 2005 you linked: they've just got two antennas, no focusing dish at all.
If someone comes along with a powerful rig, say using some of the techniques astronomers have had for many years to detect far weaker signals, what sort of distance might we be talking? It's not too far-fetched if you include possible corporate / governmental espionage attempts.
For active RFID, maybe you'd grab quite a bit.
You'd also grab quite a bit of noise. These are very low power signals; restricted by regulations in at least Australia, N.America, but it could still work. It did on 2005: http://blog.makezine.com/archive/2005/07/_defcon_rfid_world_...