The American middle class

What is the middle class? Discuss. 

"In an April 2008 survey conducted by the Pew Research center, four in 10 Americans with income below $20,000 said they were middle class, while one-third of those making more than $150,000 defined themselves as middle class." 

http://moneywatch.bnet.com/economic-news/blog/daily-money/are-you-middle-class/1728/