I totally understand your view points from the marketeer's point of view.
The reverse is also true.
I am just starting to use foursquare, I think it is great service, however, I tend to update my locations NOT real time.. just because of that, to avoid not mainly axe murderers but people whom I prefer not to meet (to be targeted)..
One thing I agree is that it is evolving.. but sadly in some ways might be in detriment of our personal/professional needs.
Privacy is paramount.. and whether credit card companies insure against it or not may help, but sadly NOT the answer..
biggest challenge is that the startup/tech field (especially online) tend to mostly focusing on slice of the value chain.. we need some further investments into the 'whole of the value chain'.. privacy is too important to have multiple holes of leakages..
Once that is achieved, the future and opportunities would be unlimited!