The opening of the American Repertory Theater’s production of “Pippin’’ was reason enough to celebrate, but the news that the musical is bound for Broadway put an even bigger smile on people’s faces at the opening night party. Among those celebrating the show’s opening were A.R.T. artistic director Diane Paulus, “Pippin’’ composer Stephen Schwartz, choreographers Chet Walker and Gypsy Snider, state Treasurer Steven Grossman, and “Glass Menagerie’’ cast members Cherry Jones and Zachary Quinto. The producers of “Pippin’’ announced this week that the show, whose original five-year run on Broadway ended in 1977, will begin performances on the Great White Way March 23 at the Music Box Theater and open April 25. . . . Bruins Hall of Famer Cam Neely had dinner Thursday at chef Christopher Coombs’s Deuxave.