I just don't think this is as big of a problem as those in tech circles seem to think it is. Facebook already has mechanisms to mitigate this; from wall updates filtered based on activity to friends lists and groups. Anyone who this was really a problem for has many options: delete unwanted "friends", ignore them, create lists for people they want to share with, create exclusion lists, create groups. People just don't seem to care that much.
Facebook has always had a "public by default" feel to it. Most people have adjusted their behavior, and their expectations, accordingly. The circles feature will take some serious marketing by Google before it becomes a killer feature for anyone but highly technical people. At that point, all facebook would have to do is make lists for visible to mitigate any mass defection. The ball will always be in facebook's court, until some major redefining feature is invented by an upstart.
Facebook has always had a "public by default" feel to it. Most people have adjusted their behavior, and their expectations, accordingly. The circles feature will take some serious marketing by Google before it becomes a killer feature for anyone but highly technical people. At that point, all facebook would have to do is make lists for visible to mitigate any mass defection. The ball will always be in facebook's court, until some major redefining feature is invented by an upstart.