Three Hollywood boutique marketing and PR agencies that include showbiz among their clients announced today they’ve formed a joint venture: Evolutionary Media Group (Jennifer Gross), Period Media (Matt Walker), and Platform Media Group (Henry Eshelman) have formed a joint venture, The Communications Partnership. While each division of the new venture will retain its brand identity, the new combo expects to cross-pollinate clients and pitches. Gross has more than 20 years’ experience in the entertainment industry. Eshelman founded PMG after 18 years with Hollywood agency BWR in 2006. Period Media installed Walker as head of flackery in 2009.