I've seen multiple variations of similar requests. It seems that there's two separate problems that need to be addressed. There's the broadcasters problem where people want to broadcast information only to select groups of people. Facebook has taken a stab at this, Google+ has done it much better, and the concept is merely Public/Private for Twitter.
Then there's the subscriber problem where people want to read relevant information on a specific topic. This problem only seems to exist when connections only need to go in one direction, i.e. following. Here users want to be able to view posts on specific subjects by those with "celebrity" type persona's. Twitter solves this (IMO, poorly) with the use of hashtags and multiple accounts. The hashtags don't solve this problem completely because you can't subscribe to a specific user's hashtag. I don't personally care that @pydanny is drunk at a wedding with Audrey, but I'm super interested in his DjangoCon talk. I also don't care about Joe Schmoe learned the power of decorators in his #django views.
To me, tags don't seem like the right approach because of the reasons above. I personally like the concept of "Channels". Users can create any number of channels for whatever they want to post about. When you are adding a user to your circle, you can select which channels you'd like to subscribe to. Then when they post they can select which channel the post is relevant to. Now, some of you may say: Whats the difference between this and tagging? Well, the distinguishing factor is that you need to create channels prior to posting to them. It forces users to categorize their subjects consistently, and it allows subscribers specific choices on what they'd like to see.
I think the issue could be easily solved by adding alternate (additional?) personalities to a profile. Then, when posting, you'd add "Markus Persson, Minecraft developer", remove "Markus Persson, default" and voila. No change to circles required, UI could be kept simple and clean, etc. I guess channels are basically the same thing, but depersonalized, and google has/wants to become people-oriented with G+, so name should matter to them.
Or let people attach search terms to people in circles.
This is an awesome analysis. I think the best thing to come out of Google+ is the clarification of kinds of digital social interactions and how we might tackle those in the (short-term) future. Maybe even Facebook or Google will iterate and offer robust solutions here.
It sounds to me like "channels" are defined by the poster, but "public group" (which I don't see you talking about anywhere on this discussion) would be taken from a global namespace. The way I choose to carve up reality is going to be slightly different from someone else's, and that difference is important.
(...and, in fact, the way I'm now reading the original poster's concept of "public circles" also seems like it is defined per-poster; but the mechanism on Flickr for "public groups" that mc32 is talking about is quite different: it requires a bunch of shared coordination over what that group means.)
(...and now I've skimmed through a bunch of your history on HN, and found that you talk about "public circles" occasionally, but do not mention "public groups", so I'm just confused. You do, however, compare them to Facebook Groups, which to me have that same global namespace problem. It is useful and important that my public circle might be called "Android Bytecode Manipulation" whereas someone else's might be called "General Instruction Manipulation", as these aren't even hierarchically related; "Sneaky Programming Hi-jinx" from someone else may be relevant and interesting to you as well; once you force things to be maintained in a public namespace it becomes a lot less personal and a lot less social in the particular "sharing is what it means to you" way that Google+ is all about.)
Read more carefully. I was not the one to compare it with Facebook Groups. We're both talking about the exact same concept. The user says, "These are groups of people that I want to send information to" and anyone who wants can add themselves to those groups.
Then there's the subscriber problem where people want to read relevant information on a specific topic. This problem only seems to exist when connections only need to go in one direction, i.e. following. Here users want to be able to view posts on specific subjects by those with "celebrity" type persona's. Twitter solves this (IMO, poorly) with the use of hashtags and multiple accounts. The hashtags don't solve this problem completely because you can't subscribe to a specific user's hashtag. I don't personally care that @pydanny is drunk at a wedding with Audrey, but I'm super interested in his DjangoCon talk. I also don't care about Joe Schmoe learned the power of decorators in his #django views.
To me, tags don't seem like the right approach because of the reasons above. I personally like the concept of "Channels". Users can create any number of channels for whatever they want to post about. When you are adding a user to your circle, you can select which channels you'd like to subscribe to. Then when they post they can select which channel the post is relevant to. Now, some of you may say: Whats the difference between this and tagging? Well, the distinguishing factor is that you need to create channels prior to posting to them. It forces users to categorize their subjects consistently, and it allows subscribers specific choices on what they'd like to see.