As stated on their website --
"Neighbornodes are group message boards on wireless nodes, placed in residential areas and open to the public. These nodes transmit signal for around 300 feet, so everyone within that range has access to the board and can read and post to it. This means that with a Neighbornode you can broadcast a message to roughly everyone whose apartment window is within 300 feet of yours (and has line of sight), and they can broadcast messages back to you. Boards are only accessible from computers that go through the local node. "