The New York Times and the Wall Street Journal acknowledged it, with their series on social class in the U.S. several years ago.
I’ve heard the term “working class” more in this presidential campaign that I’ve heard it in the past 10 years.
And now Greenwood Press acknowledges it, with the publication of this three volume encyclopedia on Class in America.
How long, then, before we can just start teaching and talking about class in schools?
Education and Class 
I think we’re hearing about class now because the middle class (or people who think of themselves as such) are being hit hard by the housing crisis, rising oil and food prices, and unemployment.