Researchers identify people through ordinary Wi-Fi routers with 99.5% accuracy

I haven't upgraded to WiFi 5 yet and it looks like being cheap|lazy is paying off.

Seriously though, this is some pretty interesting|scary stuff. This new technique doesn't require any modifications to the WiFi network at all and can even be done without authenticating. It looks like someone could just sit outside the building and track people's movement through the walls.