What this means:
- You can’t pin photos marked as private
- You can’t pin photos that are marked as being for adult audiences only
- You can’t pin photos where the Flickr user has explicitly disabled sharing
- Photos not in one of these three categories can be pinned.
Pinterest is requiring sites to individually and explicitly opt-in to "this image is not available for public sharing". In fact, the way they are providing for you to do this isn't even something that individual photo owners could have done on their own - it had to be implemented at a Flickr-wide level, rather than by photo owners. This bothers me.
As the article points out, Flickr already had a "do not share this photo" setting on their site. Pinterest should have respected it. When the next social image sharing site turns up, do they get to invent their own "do not steal" meta tag that everyone has to implement as well?