MAC address space is enough for roughly one device/square meter of Earth surface. This is about enough for wireless MAC (24 bit for longitude/latitude each) assigment from, say, WGS 84. Not enough for elevation, but given that it's rough coordinates, injecting some noise should remove potential (rare) address collisions. Pluses are the MACs can be assigned by the system (negotiating how to back off of potential collisions). Lacking relativistic pings, signal strength is useful for rough distance estimates of internode distance. Obviously, WiFi boxes which can directly parse NMEA input can compute the MAC directly, otherwise it's a one-time (for immobile nodes) operation at setup. This is obviously of use for geographic routing in wireless meshes, geographically constrained queries/broadcast, etc. -- Eugen* Leitl <a href="http://leitl.org">leitl</a> ______________________________________________________________ ICBM: 48.07078, 11.61144 http://www.leitl.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE http://moleculardevices.org http://nanomachines.net [demime 1.01d removed an attachment of type application/pgp-signature]