Predicting that it will one day replace movie posters in theaters, the Belgian theater chain Utopolis said today (Thursday) that a communications system has now been activated that will allow visitors with Bluetooth-equipped cell phones to download trailers of each of the movies playing in the theaters as well as previews of forthcoming films. In the future, the company said in a statement, moviegoers will also be able to access special promotions, including "coupons" for snacks in the concessions area. The free service, which uses a "proximity marketing" technology developed by another Belgian company, Alterwave, also reminds users to turn off their cell phones when they enter the theater.