[al-king]

I don't think he gets what makes Circles good. Their privacy and asymmetry is exactly why I like them. You don't want other people knowing 'how you classify' them, and it doesn't matter to them, really, unless they're being neurotic. Circles is an unobtrusive way to show the people you want precisely the things you want them to see; this would become an awkward tug-of-war if they had to agree on what you did.

EDIT: After a little consideration, being able to designate Circles as public does seem reasonable, though. I follow games industry, comics, and Uni club people and have them in groups saying as much. I'd feel perfectly comfortable publishing those for people who're interested, and would like to find those people.