In his blog, Bruce Schneier brings attention to the fact that a Wifi system can be used like radar: to map out the space it occupies.
This has an obvious military application, and it could easily be abused in a totalitarian state.
If the concerned general user is trying to decide between LAN or wireless for an internet connection, this fact of radar mapping is just one more factor that tells us to choose LAN.
It has long been known that the waves coming from a Wifi can be manipulated with other waves from an active attack–for various purposes.
Again, this is just one more reason to choose a hard-wired connection for a non-air-gapped system.