In a year with a highly contentious presidential election, the Olympics, and tragedy, after tragedy, after tragedy, you'd think 2012 would have been a banner year for American media. Not so. The media world is on no firmer ground than it was a year ago as it continues its quest for a sustainable business model. But that doesn't mean the industry lacked for signs of life or teachable moments in the past year. What have we learned in 2012?