Privacy doesn't exist: see http://dev.ti.com/tirex/explore/node?node=AB64dFbicd2BPc23jv...

The minute there was technology available that allowed people to see and hear through walls privacy died. It now costs less than $5,000 and if you have the right antenna you can see inside of homes from long distance and listen to people's diaphragms which allow you to listen to their inner-thoughts.

The default demo software for that particular device is to allow for listening to heartbeats but with the right modifications listening to the human diaphragm is just a matter of effort. There are people at several universities working on these kinds of imaging projects using mmwave right now even though the technology to do this has been available for over fifty years.