The announcement of Visa's new digital wallet service is being heralded as the best bet for mobile payments to enter the mainstream. Privacy concerns don't seem to play into it. After all, the bills serve as a reminder that there's essentially no such thing as a confidential electronic purchase. Yet.

Still, how much about their shopping habits are people willing to reveal when presented with a choice based on their precise positioning?

Loyalty programs offer rewards in exchange for consumer disclosure, although that requires an actual purchase being made, rather than the browsing that draws people to retailers.

The new wave of shopping applications, however, are designed to keep tabs on consumer movements from one aisle to the next.

These developments could be seen as an opt-in equivalent of the involuntary ways in which online retailers can chase your business around the web — it's never a coincidence that you keep seeing banner ads related to products you recently researched. Bringing these methods between the walls of a mall — which is still generally perceived as a public space — might be a different challenge.

For now, the companies behind location-based shopping apps are either being cautious about presenting these innovations to the public, or have some lengths left to go before they catch on. Bee Media, which first tested its surveillance at the downtown Toronto location of Canadian Tire, has stated its ambition to go global.

Some competition has emerged in the form of ShopCatch, owned by Torstar Digital, which promises to zap the coupon notifications based on exactly where your feet happen to be.

Yet the desire for a discount could also be cancelled out by a resistance to this kind of tracking. The intimacy that people feel with their mobile devices might prove too sacred to intrude upon.