That depends on your definition of "follow". You can choose to add someone to your circle without them reciprocating. In that sense, you are following them.

However, they choose which of their circles see the things they post. So you can follow whomever you want, but the people you follow may not necessarily broadcast to you if you do so.

So then it will still work like twitter if a celebrity goes on and just publishes everything as "public", then anyone can subscribe to them.

Yes, plus Circles. Circles are vital.

Circles? On Tau Day? YES.

Hadn't made the link before that, how clever :)