[secorp]

We have an open source project http://allmydata.org that has been doing this for quite awhile. I'm also involved in the commercial side which does online storage and we've been running a business on a P2P backend (nice low costs) with non-peer clients. We tried a business model with a full peer grid and users were extremely uncomfortable storing "data" from other people on their computers. Possibly the market is better educated now and/or more used to this idea, but it may be a hard sell.