I have also got the same problem within FB: Most of my friends don't care about tech/startups so I'm hesitant e.g. about commenting on Techcrunch.

Your approach sounds interesting, and it corresponds well with how you take on different personalities in different settings in real life.

Do you know of that is what Diaspora is trying to do?

I think they're doing something functionally similar, which is basically contact list management into groups. They call it "Aspects" iirc.

I think the problem with that is that it creates weirdly asynchronous or non-cohesive groups. I.e. if I have a list called work friends, it's not necessarily the same as your list called work friends, and the stuff I share to my list doesn't go to the same set of people.

In the "Places" paradigm, the groups would be more canonical and autonomous and transparent to the people in the group.

But my work friends aren't your work friends. Our friend circles might overlap but they aren't the exact same. So why should you be posting to my work friends group? Don't get me wrong - I think you have an interesting concept here, I'm just trying to understand it better. (I wrote Friendika, which is kind of like Diaspora but a bit more capable - I could probably make something like this happen.).

Well, if we don't work together, we wouldn't share a work friends group.

It's true that a places metaphor is a bit less granular, but I think it makes it easier to understand how things are being shared than a bunch of one to many connections that overlap to varying degrees.

Also, there's no reason you couldn't have both, since the places metaphor is really in practice just a subset of everyone having individual group lists.