He told me about an RFP they got from a large retailer. (He didn't say which one.) They want to install a grid of little cameras on the ceiling of their stores that can track people as they walk around the store, starting from when they walk in the door until they leave. The grid would be self-organizing, adjacent cameras talking to each other and handing off trackees to each other. It couldn't recognize people, although if you buy something with something other than cash, it'd know who you were from that transaction. This isn't intended for loss control (retailese for shoplifting) but more for marketing. They could, for example, rent a rack in a prominent position to a supplier, and charge them by the number of people who stop to look at it.

But wait, there's more!

In agricultural areas with high-value crops like wine grapes, it's long been common to fly over the vineyard (or whatever) in a small plane like a Cessna 172 with a camera pointed down at the crops, to tell what areas are looking more or less healthy and might need more water, fertilizer, or pesticides. Cessnas with pilots are fairly expensive, so more recently someone has come up with a miniature automated camera drone that the FAA considers to be a model plane, meaning that they can fly it just about anywhere other than at an airport, and it's small enough that when it's flying at its typical altitude, it's invisible from the ground. Splice these two systems together, and you have a grid of invisible midget spy planes tracking people anywhere, any time.

This is all technology that exists today. He didn't say it's been deployed in this form, but all it needs is someone with the money to commission it. Wow, that's creepy.