Nate Silver at fivethirtyeight.com unearthed this amazing statistic:

In 1980, 32 percent of the electorate consisted of white Democrats (or at least white Carter voters) — likewise, in 2008, 32 percent of the electorate consisted of white Obama voters. But whereas, in 1980, just 9 percent of the electorate were nonwhite Carter voters, 21 percent of the electorate were nonwhite Obama voters last year. Thus, Carter went down to a landslide defeat, whereas Obama defeated John McCain by a healthy margin.