<p>Rush wasn't built in a day. That's Michael Harrison's take on this week's announcement by Progress Radio that it had signed comedian/author Al Franken for a daily show intended to provide a liberal challenge to the medium's 600-station gorilla, Rush Limbaugh. The founder and editor of Talkers magazine, the industry's lead trade journal, says that if Progress Radio fails it will be because of the impossibly high expectations it has set for itself.</p>