As Poynter's Rick Edmonds noted last fall, "deal of the day" services show how retailers are moving from mass advertising to direct marketing. Now those groupon coupons services are threatened by Facebook Deals, just launched in five U.S. cities. Marshall Kirkpatrick describes how Facebook's massive user base, demographic information and location check-in could make "roadkill" out of Groupon and LivingSocial. Users will learn about Facebook Deals through their news feeds, not simply email. "Groupon and Living Social offer nothing but deals," Kirkpatrick writes. "Facebook puts deals in between pictures of your sister's baby. Which do you think you'll click through more often, all other things being equal?" A key advantage for retailers: While competitors take a share of revenue, Facebook Deals may be free. Whoops: TechCrunch learns about Deals launch through a New York Times slipup. || Earlier: Groupon offers opportunities and threats for newspaper advertising. || The dark side: Groupon deal financially crippled small bakery.