I've just hit an interesting problem. If you restrict audience access by age or country, your posts are no longer fully public. Which means they no longer turn up in an API request for activities.list because the only collection type allowed is "public".

This then means my G+ to Atom code doesn't work and neither does dlvr.it to grab the posts and take them elsewhere. Which is somewhat annoying.

I can see the logic, but it means that the API cannot be used to access posts that are not fully open and apparently Google doesn't or can't use the initial authorisation to work out if the calling program should have been able to access the post.