Two artists have bugged a number of them in order to post the conversations of random passers-by on Twitter.
Sound sinister? Well, it kind of is.
Kyle McDonald and Brian House call their project 'Conversnitch' and it's designed to make people think about surveillance.
House told Wired: "What does it mean to deploy one of these in a library, a public square, someone’s bedroom? What kind of power relationship does it set up?
"And what does this stream of tweets mean if it’s not set up by an artist but by the U.S. government?"
Most of the captured snippets are pretty mundane and lack context...
But some are genuinely interesting snapshots into the lives of others that allow your imagination to fill in the blanks and create your own narratives...
Obviously the project has parallels with real life.
McDonald said: "You can’t make this stuff up anymore.
"Here were Brian and I trying to make something kind of scary, something that makes you wonder if someone’s watching you all the time. And then Snowden says, ‘They are."
To find out how they went about the project watch the video above...