Fisrt, thanks for sharing this: http://thesocialopac.net/. It's really nice way to find some help. I agree with you about the law's problem. We can solve it with some option for user to choose like "sharing you action to your friends, not sharing...". And if u ask, where we can put this Wall on the Opac website, i think we can creat one more little menu like- "My friend's action" above the "My summary" on the menu. We can make a default like sharing your actions with your classmates (for shool's library or university's library). After friend's action, you can comment, like (it looks like in facebook). I think, the main idea is that, you can share your opinion about some books, recommend it to friends... We did have all databases, how can we make it comes true? I hope some programmer can do it and i think they really can. Best regard!