The Collaborative International Dictionary of English v.0.48:

faddish \faddish\ faddy \faddy\adj.
   1. intensely fashionable for a short time. [WordNet sense 1]

   Syn: trendy. [WordNet 1.5]

   2. prone to follow fads; as, a faddish clique of teenagers;
      -- of people.

   Syn: trendy. [PJC]

WordNet (r) 3.0 (2006):

faddy
    adj 1: intensely fashionable for a short time [syn: faddish,
           faddy]