Nice article about Google, Jaiku and the future (via Dragos), Nokia has been doing this for ages (at least 3 years back), too bad it never "took off" - the main reason for that is in my opinion not partnering with carriers to use their Nokia Presence Server.

Nokia had also pioneered bluetooth social networking with Nokia Sensor, again a very old application that has never been successful despite being backed by the famous mobile phone company, this should be a lesson to learn for the followers.