This discussion is YEARS too late, folks. Privacy is an almost extinct species. When you fired up your first computer and set up an Internet account you lost most of it. When you got your first cell phone you lost some more, and the smart phones combine the two. That's not conspiracy theorizing, which I generally find laughable, it's simple fact. When you use your courtesy card at the supermarket or stop-and-rob your purchase goes into a database. Marketers everywhere can tap into all kinds of data about you, your buying habits, where you live, and on and on.
Cameras in public places are the least of my worries. No, they didn't prevent the Boston bombing. They may bring the twisted animals who did it to justice, and that's damned important. I'm not talking about the speed-trap kind, but the ones that observe public behavior that is on view anyway. If they bust one thug who mugs an old lady or someone handicapped, I think that's great even if they didn't prevent the crime.
Rather than worrying about loss of privacy in out-in-the-open actions in public space, think about how much all kinds of crooked marketers already know about what you do in your home.