Microsoft have been making a lot of money this generation on their Xbox Live Gold membership rates, while Sony have kept their service free of charge.
However, according to information in survey conducted by Sony it seems online multiplayer will still be kept free. The premium members will get access to demos early, exclusive extra matierals, cross game voice chat, music sharing, and more.
There are also rumours that parts of the PSOne Classics and Minis selection will be free for premium account holders (although it does seem like a bit of wishful thinking).
Rumours have the service at somewhere between $29.99 to $69.99 annually. But its only rumours at this point.