My issue with that is the first great online walled garden was AOL and they were competing against (using and cutting off) SMTP.  So there was a ready made, open, federated solution waiting to burst out.<p>Whereas in Facebook, Google etc, the open solution is usually following the walled garden.  I yearn for open solutions but they will have to follow open internet access (local grids) and then the economics of sending a packet to SF in order to message my next door neighbour becomes more obvious.