I'd like a clarification from somebody who uses Reader / Picassa. Is any of the stuff that's suddenly available to following people actually private, in the sense of impossible to access? Or simply "obscure", i.e. if you know the username and look for it you can find it?
Wrong -- it adds the list of people you exchange email with to the list of people you follow, which is publicly visible by default. There was no way for anyone to see who you exchange email with until this happened.
The fact that you can go back and block your "following" list from public view is irrelevant -- the list of people you exchange email with should never have been put on that list without your explicit consent. It's a unilateral change in the terms of the agreement you have with Google. Letting Google publish a list of people I follow in Google Reader is consent to publish a list of people I follow in Google Reader -- it is NOT consent to publish a list of people I email or who email me.
