"Not only is RSS being used as an ad medium by companies ranging from Google to Pheedo, it's now an official marketing tool," writes ClickZ's Rebecca Lieb and provides and excellent overview of how RSS is being used by marketers "in real life and real time." She quickly notes that browsers, portals and operating systems are integrating RSS and goes on to cover marketing efforts making use of RSS, including coupon feeds, affiliate marketing, PR, classifieds, podcasts, and branded content.