WordNet (r) 3.0 (2006):

socialite
    n 1: a socially prominent person

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "socialite":
   Beau Brummel, arbiter of fashion, clotheshorse, clubman, clubwoman,
   dandy, deb, debutante, fashion plate, fashionable, fop,
   man-about-town, mondain, mondaine, subdeb, subdebutante, swinger,
   taste-maker, tone-setter, trend-setter