As expected, Facebook has started displaying ads in users' News Feeds. You may not be seeing them yet as the company is rolling them out gradually, like it does for all its changes. ... Last month, a Facebook spokesperson said the company hoped to 'show people no more than one Sponsored Story in their News Feeds per day.' This is no longer the case, as Facebook now says you may see more Featured stories 'if you visit your News Feed a lot.
http://www.zdnet.com/blog/facebook/facebook-starts-displaying-ads-in-the-news-feed/7143
http://techcrunch.com/2011/12/20/sponsored-stories-news-feed/
http://www.zdnet.com/blog/facebook/facebook-starts-displaying-ads-in-the-news-feed/7143
http://techcrunch.com/2011/12/20/sponsored-stories-news-feed/