My theory is that it's deliberately quarantined. Think about it -- if the server just obeyed whatever silly links you put in your sig and fetched them all, finding out where it is and who owns it would be trivial. From there SR is just a hop and a skip away. So it can't be the server downloading the image and caching it.Could be the client doing it, to be sure. Just another image link to go off and download while putting together the final page. But if that's the case, then (like you and me) most people will only see the alt text and not the image. So in other words, I don't think it's gonna work.