[Animats]

No, the early Internet economy tried micropayments. First Virtual, Cybercoin, Millicent, Digicash, Internet Dollar, Beenz...

All failed.

Anyway, payment isn't the problem with distributed social networks. Asshole amplification is the problem. If one jerk can easily annoy hundreds of users, there's a problem. Trying to build a federated social network which can survive spam nodes is going to be tough. Especially if users are anonymous and can create additional identities easily.