Some replies to your comments
Hi all - I am Ben Birt, the developer of PeerBook. I'm amazed this story made it onto The Reg! I'd just like to reply to a few of the above comments:
Firstly, I do love the IT crowd - especially the FriendFace episode!
Stevie: Of course the assumption that malicious users exist is built into the design of PeerBook. Every piece of data is encrypted with keys that can be changed at will. So while a user does not really have any control over where exactly on the p2p network their data is placed, it doesn't matter - if you don't have access to the data, even if your computer is being used as the temporary store for that data, you can never read the data. I'd also like to point out that at no point have I asked for any donations whatsoever.
notmenotmenotme: Yes, I have been following the Diaspora story. The key difference between our two projects that I can discern is that Diaspora requires you to host your own data 24/7 - meaning that you must either keep your server on permanently or pay for some hosting somewhere. This certainly makes the whole problem of remote data storage + complex access control policies go away, but I do not believe it is a good enough solution to replace existing social networks which. I have actually emailed the Diaspora team, but they did not reply.
serviceWithASmile: Thank you for your post, you are quite correct - the software runs almost exactly as you say, but uses a more lightweight web server than Tomcat (because I didn't want potential users to have to do anything complex upon installation).
Thanks. If anyone has any more questions, please ask away. And feel free to read some of the stuff on the PeerBook website/blog that I am (slowly) adding to: http://blogs.cs.st-andrews.ac.uk/peerbook/