SSB's central premise -- distributed users, making an ad-hoc network connection whenever they are physically close, or perhaps have some network connection -- b

SSB's central premise -- distributed users, making an ad-hoc network connection whenever they are physically close, or perhaps have some network connection -- bakes in an assumption that a user's ability to connect to the network is sporadic. It seems like the system would work just as well for people who decide to turn their system off when they go to work, or are on a sailboat. Of course it's not convenient in the same way that always-on social networks are, but that seems to be specifically not the point of SSB.