http://www.infoq.com/presentations/private-backend
tl;dw: next time you build a webservice, let your users use private drive, dropbox, or whatever accounts to host their data (or at least the data that doesn't get JOINed to other tables all over the place). one has to pay for data ownership, but it's not per-service charge.
the article's kind of a tease. it's easy to say things like "open" and "decentralized," but i guess if i want to know what specific implementations were discussed, i'd have to buy the magazine.