About: Cal Henderson has been a web applications developer for far too long and should really start looking for a serious job. Originally from London, he currently works at Yahoo! Inc. as the architect and development lead for Flickr. He formed part of the original Flickr team at Ludicorp in Vancouver, Canada. Before Flickr, he was the technical director of Special Web Projects at Emap, a UK media company. Outside of Flickr, he contributes to several open source projects and writes occasional articles about web application development and security.