Estimote, a YC startup that offers iBeacon solutions, was providing such a system at their inception when I met them in Poland back in 2011. Whilst a bit baffled at first ("you can track me without my knowledge with such precision?"), I began to understand all the possibilities that this could offer, some sort of Google Analytics for Real Life.
No, I hadn't thought of queue management, but airports are one of the only place where, to simplify, a provider knows pretty much when its customers will arrive in its premises (you have to clear check-in and security) in which they'll have to stay for a defined period of time. Having the ability to understand how they move around, what are the heat maps within existing constraints, what are the usual patterns, etc. opens the door to a lot of design thinking opportunities.
With an estimated 81% of passengers carrying a smartphone compared to 25% five years ago, according to SITA's report The Future is Personal, and with a renewal rate of roughly 18 months, there's no denying the appeal of such technologies for airports, much much cheaper than the traditional camera-based ones big retailers have been using. And Blip doesn't limit the idea to the usual pain points, see for yourself: