‘Footpath technology’ is (perhaps) the most recent entrant regarding how retailers can track any given consumers movements / patterns (within a shopping mall; store, etc.) that’s likely to come under increasing government scrutiny (especially if it is employed on unsuspecting end-users) as NFC (and related technologies) is / are still hard-pressed to demonstrate how best to strike a balance between cutting edge vs. an invasion of privacy.
(Source) WSJ: http://goo.gl/rY1M2