What I miss is some website where I can choose who gets to read what I write: this post is for everbody, this is only for my family, this is for my work mates, this is for the general public, this is for my brother.
The advantage of this would be that you could move groups over one at a time (since they would get some benefit from it, people would want to use it) and it is something facebook can't do and don't want to.
Try this site out: http://www.facebook.com/ - they have a nifty feature that does exactly that.
(1) You share your birthday with a friend Bob.
(2) Your friend Bob installs a facebook game from the Sleazo Company.
(3) Sleazo Company now knows your birthday.
That's how I understand it works. Your friends can share your information with third-party facebook applications. Please correct me if I am wrong.
Unless we're willing to consider DRM for social networks, this won't change with Diaspora or any other kind of software that puts your birthday on Bobs computer in any kind of standardized format.
At the same time he makes huge mental leaps that I completely disagree with (he said basically the same thing about open source/open culture) but there are several gems in the book.