As a general rule, when you go outside, you've temporarily forfeited your right to personal privacy. If you're walking down the street on your cell phone, talking about the affair you're having, you have no true recourse if someone hears you and informs your spouse. If you throw bank documents into your trash and then put your trash on your curb, you have given other people permission to go through it and sift out things that might be of interest. I'm not necessarily stating that I embrace this concept. No part of me wants my neighbors sifting through my financial aid paperwork, for example. (My prevention technique is repeated layers of coffee grounds. Enough of them and even the most dedicated sifter will give up and go home. Crockett's much-less-interesting-but-slightly-more-effective technique is shredding everything.)
The point, I think, is that if you want something to remain a secret, you need to keep it under your control. Don't want someone to know you were at a certain bar? Wear a hat and a fake mustache, because there will be people there, and some of them might know you, or have camera phones and an itchy tweet thumb. I've tweeted images that had strangers in them more than once, so it's not outside the realm of possibility. Don't want love letters falling into the wrong hands? For heaven's sake, either keep them yourself or burn/shred/coffee soak them.
Can we apply the same rules to privacy on the web? If you don't want everyone knowing something, can you keep it in an email instead of putting it on a facebook wall? If you want your opinions to stay yours, can you just avoid becoming a blogger?
The public internet has become a place that has no reasonable expectation of privacy. That's sort of the point.
Is that ok? I don't know. Do you think so?