I've noticed while I'm out and about (specifically at HyVee and Walmart) that the Continuity prompt (bottom-left corner of the lock screen) shows the App Store. When I open it, it takes me to their respective apps to be downloaded.
I thought that Continuity only shared to other devices with your Apple ID, so how are they advertising their apps? Are they receiving App Store links from nearby iBeacons? Various Google Search terms haven't turned up any information.
This is the new Suggested Apps feature of iOS 8. This is an AppStore feature that uses geofences (not beacons) to find apps relevant to your location. The description of this feature in settings says:
Leaving this option turned on will allow iOS to offer suggestions for App Store apps that you do not already have installed. These can be based on what you already have installed or what people near you find interesting.
Apple's mechanism for suggesting apps is undocumented. Perhaps it is based on an algorithm (other folks regularly using an app in the vicinity), a database (known locations of major retailers), or paid marketing (e.g. Starbucks pays Apple to suggest their app when near one of their shops.) It could be a combination of all three.
I know that this technology is not based on beacons (at least not exclusively) because I received an app suggestion for Starbucks (without having the app installed) and then I immediately used a non-iOS-based beacon scanner that verified no beacons were in the vicinity.