OK, Facebook is bringing Beacon back in the next 6 to 12 months, with plans to charge advertisers when Facebook users buy their products. We're sure social-graph enthusiasts are enthused. But for those trying to make money with Facebook widgets now, there's better news today. With the launch of a new "Demographic Restrictions capability" that can tell under-21 users from over-21 users, Facebook has decided to allow itself and widgetmakers to sell ads to the alcoholic-beverage industry. You know, the one known to spend as much as $915 million a year on beer ads, and which might be keen to reach Facebook's college-and-after demographic