Interesting. This is similar to an idea I've had for a privacy-sensitive version of Facebook ("Faceless"?) that uses public key encryption at the client to pre

Interesting. This is similar to an idea I've had for a privacy-sensitive version of Facebook ("Faceless"?) that uses public key encryption at the client to prevent the servers from being able to read anything posted. When you post new content to your friend list, your client uses your private key & your friends' public keys to post a separate encrypted copy of the content for each friend. Thus only they (and you) can read the content. Note before people point out all the flaws in this idea =)... I'm aware that this would have problems on the key management side of things, plus one-encrypted-post-per-friend would get computationally (and bandwidth) intensive as your friend list (or "circle") increased in size. I'm also not convinced people actually want this - Facebook has made it abundantly clear that most people don't care about online privacy. I would use it, though!