I feel you. I think the "drinking photos" example is illustrative because it's extreme, but I think the real, widespread pain points --- I know the ones I have

I feel you. I think the "drinking photos" example is illustrative because it's extreme, but I think the real, widespread pain points --- I know the ones I have, at least --- are more along the lines you mentioned. Sure, you can put up certain walls relatively easy (i.e. only these friends can see my pictures). But I think you hit on the essence of contextual sharing, which is that privacy aside, you simply want to share different things with different people. I want to share the Paul Graham essay with only my start-up friends, I want to share the new NoSQL db github link with only my hacker friends, I want to talk smack about fantasy football with only those people, I want to post my family vacation pictures to only my family, etc.