alt Hacker NewsA bit of an off-topic, but the social networking protocol should never be designed for the sake of the protocol itself, or it’ll not enjoy the networking effect. A protocol must offer direct benefits to users, so that they keep participating in the network. This participation is what eventually forms the network of people, a.k.a, society. I always pick BitTorrent as the most successful example of such networking protocol - people just wanted to download stuffs (e.g. movies and pxxxs) but ends up participating in the sharing network.
Personally, I think a possible angle of attack for a new practical social network protocol is data management, as the amount of data people generate, consume, store, and share is enormous these days. More like, manage data conveniently, and share them easily as a side-effect.
I think a good protocol however is key for adoption. Many a good idea has died an early death because the implementation of it was, too complex, insufficiently robust, or poorly thought out for the future.