You're going to hear a lot about independent voters this election season. They will no doubt tip the balance in the November presidential contest, determining the next occupant of the White House. But who are these Americans? What share of the electorate do they represent? And what drives their vote choice? A closer look at this important electoral bloc reveals some startling facts and underscores why "independent" voters are among the most unpredictable when it comes to political forecasting. I've been writing for the past couple of weeks about the changing nature of the American electorate. Winning in 2008 requires...