How is this different from cops doing a stake out? They don't need a warrent or your permsion/knowledge to follow you around and check on your whereabouts, so why is this any different than that?
Seriously, this is right up there with the "theory" that the goverment can track your car and listen to your converstaions via OnStar because the goverment now "owns" GM.
There is that whole 4th admendment thing you know.