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.
Additionally, Neighbornodes are linked together, making up a node network to enable the passing of news and information on a street-by-street basis throughout the wider community. With access to your local Neighbornode, you can post messages to your local group board, as well as forward messages to other nodes in your vicinity. These other nodes can in turn forward messages to your node, resulting in a network of neighborhood message boards. [blogged by Samuel Rose on Smart Mobs]