The messages posted in public are not private, yes. Any private data involved in my signing up with those services, though, should remain private. I don't post my credit card numbers or social security number, and many people don't post their real addresses, etc.

I think there needs to be a mechanism for individuals to control their data more globally, though. The "Anonymity War" which is part of the background of my new book Grand Central Arena is based around that idea.