Musical theater legend Stephen Sondheim's 80th birthday last spring has sparked a couple of upcoming tributes in Northeast Ohio. They include Great Lakes Theater Festival's collaboration with Playhouse-Square to produce the revue Sondheim on Sondheim in May 2012 and — just around the corner — Fairmount Center for the Arts' production of Sondheim's Company, opening April 28 at Mayfield Village Civic Center.