Today's a big day for users of Creative Commons images: Flickr has declared zero tolerance for copyleft trolls, predators who exploit a bug in out-of-date versions of the CC licenses in order to threaten good-faith users of CC images who make minor errors in the way they credit the images.

First things first: Flickr's new community guidelines prohibit copyleft trolling: "Failure to allow a good faith reuser the opportunity to correct errors is against the intent of the license and not in line with the values of our community, and can result in your account being removed."