> Centrally hosted data storage may have better availability, but the cost is prohibitive.
Yes, as soon as you go over the 50GB limit cloud backup space starts to cost real money (at least for endusers small budgets). Being able to plug a cheap USB disk into your WLAN router and use that as webdav is nice and cheap if you can live with the kind of reliability it gives.
> users could even backup other users' data, which is where projects such as owncloud can help.
Isn't that what things like Wuala do? a P2P backup sytem?