I think this is the crux of why G+ failed. When I first started using it, circles seemed like a killer feature. I divided all my contacts into work, friends, family, by location, etc. So I could share programming stuff with tech friends, but local stuff with local friends.

But, instead, I find I just share everything I care to share public. I think what people share is part of how they present themselves, and if I'm always in the context of being myself, with my real name and the same picture, then I'm going to share the same set of stuff.