Distributed Databases?

yamla asks: "I am interested in learning about distributed, fault-tolerant databases. That is, a database (not necessarily SQL) where the data is spread out (not replicated) amongst a large number of computers and furthermore, any reasonable number of those computers could disconnect or reconnect at any time without making it impossible to retrieve the stored data. I think this is a far more interesting problem than peer-to-peer because, provided such a solution scales, it would seem to solve the decentralised peer-to-peer problems. It would also seem to open up all kinds of new applications which we have hardly begun to think about yet. So I'm interested in good places to go to read up on (potential) solutions."