I wrote that you can't upload pictures of random punters on the street to your Flickr, Facebook or blog account without their express permission. That's because their image is part of their personal data. A lot of people seemed to be unaware of this. And it does seem a little weird. Nevertheless, that's the way it is.
Here's the section of data protection law that deals with it. I had a chat with them to confirm it, too, in case there was any misunderstanding. (They've already taken action against people uploading videos to YouTube without getting consent from those identifiable in it.)