BlueStates (see also here) by Mark Pesce, John Tonkin, an artwork presented at ISEA2006 that "art project which uses bluetooth - wireless networking found in many mobile phones and personal computers - to sense social relationships and, from that, to build an emergent model of an individual's social network".

BlueStates is by its nature a highly participatory work. Anyone will be able to visit the website - at http://relationalspace.org/ - and create their own views into relational space. Residents of cities around the world will be encouraged to add their own sensors to the global network of sensors, expanding the database to incorporate the inner social life of their own cities. Beyond this, the work's creators have committed to releasing all software developed for the project as as free and open source software (under the GNU General Public License), believing this will encourage others to create their own projects in relational space. Finally, artists will be provided with tools to that will allow them to permute the data gathered by BlueStates: Exploring Relational Space in new and unique ways.

Visualizations would be like:

In this case, a scanner named "Minerva" has found a number of other Bluetooth devices in close proximity to it, named "Hermes", "Hermione", "johnt-phone", and several others. Because Bluetooth signals are very low-power, a scanner can only sense other Bluetooth devices within a radius of anywhere from 15 to 50 feet from the scanner - so each of these devices were within 50 feet of the scanner. The scanner then sends the results of the roll call back to the bluestates database. Computers running the scanner software use their internet connection to send roll-call data to our database.

Why do I blog this? this is yet another relevant product with regards to location-sensing in city contexts; it's also related to my work (to be included in my phd chapter about location-awareness applications) since I am categorizing those interfaces.