I reported about 30 hours ago at the Search Engine Watch blog that AdWords Adds Click to Call Feature to Ads where you get a little phone icon, that allows you to click on the ad, type in your phone number and hit connect for free, then someone should call you. More information at http://www.google.com/help/faq_clicktocall.html.
Forum discussion at Search Engine Roundtable Forums and DigitalPoint Forums.