It seems circles are curated only by their creator. What is some circles were publicly listed with an opt-in button for recipients (with an optional approval step by the circle creator).
Here’s the example: a lot of my photo stream is endless pictures of cute kids. Facebook friends who have friended me for other topics have to wade through that collection. Some actually like them – our friendships aren’t single issue and they appreciate glimpses of the rest of my life. But with G+ it’s my job to figure out which issue friends might want to be kid picture friends. I don’t want to put them on a list they don’t like and essentially spam them. Is there any G+ features I might use?
Google+: View post on Google+
You can ask people that. I asked who wanted to be in my activist circle because those people will get more directed messages. Many people opted-in.
I do like the idea of a public circle. Obviously this would be useful for groups such as QQ, etc.