orijing (the engineer at Facebook) is right in that you do have to auth the app.
It's not as though could be browsing one day in search of "abortions Chicago" or "genital warts" and have that auto-published to your FB page. You'd have to give an app explicit permission to share activities on your behalf.
I think the point is that you could sign up with LocalTimes' funky new daily deals site using Facebook Connect one day, clicking through a generic permissions screen as you do, because you trust LocalTimes aren't going to do anything spammy. If you know what the signup permissions mean (which if you're an average person, you don't) you decide you can live with some of your friends wondering whether you bought the half price pedicure you perused.
A month later, you're Googling for a local STI clinic and have no reason to believe that clicking on the top result (LocalTimes' eclassified section) is going to share your interest in local STI clinics with all your social network. But it is, because LocalTimes' single signon site which you're already logged into makes no distinction about what is and isn't to be shared, but they have made efforts to adopt this revolutionary new form of passive sharing which is going to push up their pageviews.
But I think the OP's point is that privacy will eventually fade away, so if I'm doing a Google search on "cure for HPV" this will be published publicly to my Facebook profile. I don't really care that "oh, it doesn't publish automatically unless you grant it permission!". I want to be notified when something is posted on my profile.
On another note, I'm seriously considering closing my FB account once and for good and leaving for G+. I have a good crowd of friends willing to do this (and invite their friends), but G+ offers no way to import FB data, which would be a nice feature.
I don't understand. You're afraid that your Google searches will be published to your Facebook stream, so you want to close your FB account and move to G+, because presumably Google is less likely to publish to your G+ profile than to your Facebook profile?
And what if Facebook decides that apps no longer need permission to access profiles? They don't care about using privacy /at all/. They purposely make the privacy controls hard to use.
It's not as though could be browsing one day in search of "abortions Chicago" or "genital warts" and have that auto-published to your FB page. You'd have to give an app explicit permission to share activities on your behalf.