The People in Photos feature that Flickr just rolled out has been much fun to play with. I've spent some time adding this new metadata to mine and many other photos. Some people have marked their photostream to not allow it, and some people have asked to not be identified. That request gets honored, but it's pretty much pointless. It won't be too many more years before automatic recognizers just get run over all photo and video sources, both live and historical. You will be tagged and identified, the only question is do you want access to your metadata as well. It will exist anyway. (But it's not terribly useful to point that out to people who think that by asking, it won't happen...)
I had an odd exchange a few days ago with a friend of a friend, which I am still musing over. It ended with me saying "it sounds to me like you maintain your relationship with a GROUP of people, instead of a set of individual relationships with individual people." (The middle part of the discussion was about my serious discomfort with observing that something looked like a self-selecting closed set "are you cool enough to be one of us" "cool kids" clique.) Anyway, her response was "that's the only way I can maintain a relationship with as many people at once as I want to have".
I can't tell if this is just a world-view difference between us, or a failure of communication and understanding, or something I've been "doing wrong" all these years. Maybe it's just that I don't much care for the "cool kids clique" attitude. But then, every handful of years, I get to learn the hard and painful way, that trust isn't transitive, that friendship isn't transitive, and that even fellowship isn't transitive.