For the first time ever, wheat bread has outstripped white bread in total sales. It's a significant shift in consumer preferences, as Americans have long favored the whiter, less-nutritious loaf. So what accounts for the change? According to Chicago Tribune reporter Emily Bryson, it's all about product messaging:

Flooded with messages about heart health, fiber intake and the need for omega-3s, more consumers are looking for bread that can taste good and deliver nutrients... It's part of a major turning of the tide. Packaged wheat bread recently surpassed white bread in dollar sales, according to Nielsen Co. For the 52 weeks ended July 10, wheat bread sales increased 0.6 percent to $2.6 billion, while white bread sales declined 7 percent to $2.5 billion. White bread is still ahead in volume, but the margin is shrinking. Americans bought 1.5 billion packages of white bread in the last year, a 3 percent decrease, and 1.3 billion packages of wheat bread, a 5 percent increase.
Taking in the news, Carey Alexander at The Consumerist is dumbfounded:
We find it tough to believe. Back in our day, white bread was what you ate to fight communists. Peanut butter and jelly on wheat bread? Please. Now, consumers care about what is cheap and what is healthy. 
Perhaps the Cold War really is over.