Let's say I share something with a circle "family" and the circle contains some people that haven't signed up for Google+, so I just have their e-mail address.
When these not-yet-plussers sign up for Google+, will they then be able to see my posts from before they signed up? What about when I share a photo album to this "family" circle?
I assume that if a user eventually sign up to Google+ but uses a different address than what I have in my circle, then they can't see any of my posts (unless they're also public).