You can click +1 and then click on the grey "Share on Google+" to select to which circle you want to share.
The +1 is public +1 which not all of us want to do.
Indeed, very annoying. I want to share stuff with my friends and love the granular approach I can now take but if it means I publicly have to +1 it. I have no idea how public that is, can people see a list of all things I +1'd? Can friends?
The non-public sharing is in the top right of your screen.