I just got an invitation to join Brightkite, a private beta location based social network. From the outset the system seems to mirror Dodgeball, a three year old Mososo built by friends Dennis Crowley and Alex.
After playing with Brightkite I really do not see a whole lot of difference between it and other mososos I have seen in the past. The infuriating thing that this system may prevent is what Dennis calls the Ex-girlfriend situation. Once in a circle, always in a circle. It is the quintessential example of how technology does not always play nice with the social realties and proclivities of users.
I will give Brightkite a point for integrating other social space lists to help you connect with existing connections in new spaces. One of the more frustrating things when you experiment with a new system is trying to hunt down all of your real friends. I put in my Twitter user name and found a number of folks I would like to know their whereabouts, particularly during a conference. The heart breaking thing is that Verizon does not support the Brightkite platform yet. But like most innovations most people 'get it' after a while.