Ruby K. Payne makes a lot of money explaining class to rich folks in capitalism-friendly ways. I thought she'd been thoroughly debunked in 2005, but I just saw her cited in a 2012 Wiscon panel about class—which, I realize, says more about fandom's social justice warriors than it does about Payne.
Still, should she come up again, here are some useful links:
Education and Class (Exploring the intersections of social class, education and identity): posts about Ruby Payne.
Savage Unrealities: Uncovering Classism in Ruby Payne’s Framework by Paul C. Gorski.
Beware outside consultants? – Part 2, Ruby Payne | Dangerously Irrelevant