A UK shopping centre is using the signal from its customer’s mobile phones to monitor people in the building.

The technology can tell when people enter a shopping centre, what stores they visit, how long they remain there, and what route they take as they walked around.
- via Times Online

This uber level of customer surveillance will be used by the centres by aggregating the customer data to better understand behaviour of people to assist with promotions, shopping centre design and providing centre services.

While right now, info that would reveal your personal identity will not be transmitted or stored, it is still creepy and feels like one last step before enabling Minority Report style hyper-targeted advertising.