Facebook are linking their Advertising to store visits according to AdWeek and Adage.
So you can track who sees the Ad and whether they visit the shop!
Which means, targeted local awareness Ads (say an Offer) using GPS, as people walk near a shop, can be proved effective.
Ideal to capitalise on mobile usage too. Real Advertising delivery and effectiveness.
However, people will have to opt-in for GPS tracking on an App but that should be overcome as an add-on to the Facebook App. They're also rolling out a feature called 'Store Locator' giving shoppers detail info on the nearest shops etc. so that will fit the GPS bill too.
If you know where people are at any given time, you can Advertise to them and measure the actual return through a visit. Next of course, will be adding in the transaction.
Facebook's Offline Conversions already does that to a point where transactions are over Mobile.
It's all pretty brilliant really.