They don’t play instruments, paint landscapes, or take bows, but those wealthy men and women who sped their evenings in formalwear, going from cocktail party to reception to gala, are an integral part of any city’s cultural scene. In tony Boston, the glitterati have traditionally formed a very exclusive club, but things are changing. “Gone are the closed ranks of the Boston Brahmin, when your place in the Social Register was a question of pedigree. Today, membership in the club is more dependent on how much you can do — and give — for worthy causes. And, with the pool of local corporate benefactors shrinking through mergers and out-of-town ownership, the donations from this club are becoming more critical to a wide array of the city’s social services and the arts.”