[noelwelsh]

iBeacon (https://en.wikipedia.org/wiki/IBeacon) is one way to achieve this, but AFAIK it hasn't had much adoption. If I was doing this I'd probably first look at video tracking via existing CCTV cameras, possibly augmented with information like iBeacon.

The book "Why We Buy" gives examples of how manipulating sight lines and visitor flow through stores can increase sales. If you could track visitor paths continuously you could continually optimise your store layout, rather than doing a one-off with outside consultants. Think of it as the offline equivalent of continuous A/B testing.