And double scullers David Crawshay and Scott Brennan led throughout to take Australia's second gold of the day.
Ginn, 33, won gold in the coxless four in Atlanta and missed out on home water four years later before moving into the pair successfully in Athens in 2004.
Canadian duo Scott Frandsen and David Calder led early but the Aussie pair came through, with New Zealand third.
Crawshay and Brennan stayed out in front as Estonia and Great Britain battled for the silver medal, Estonia snatching second place in the final few strokes.
Kiwi Rob Waddell, the Sydney 2000 singles champion who returned to rowing after several years with New Zealand's America's Cup team, was pushed into fourth with partner Nathan Cohen.
Estonia's Tonu Endrekson and Juri Jaanson celebrate on the podium during the medal ceremony for the men's double sculls final at the Shunyi Rowing and Canoeing Park during the 2008 Beijing Olympic Games in Beijing on August 16, 2008. Australia won gold, Estonia silver and Britain silver.
Photo credit should read FRED DUFOUR/AFP/Getty Images