Stolen from CNET. (Warning, technical geek info ahead. If you dont do that sort of thing you wont be interested.)
http://news.cnet.com/8301-17938_105-...?tag=cnetRiver
(Before you post, "but wait, he could have bought one for like 30$." Thats not the point. He made his which is infinitely more impressive than any bike computer purchased.