According to a team of economists headed by Jeremy Greenwood of the University of Pennsylvania, the more educated people are, the more likely they are to be married to a partner of similar education. Those with less education are also likely to be married to a spouse with less education. Back in the 1960s that might not have been too big of a deal since a husband and wife with a high school education would earn 103% of the average household income. Unfortunately, in 2005 (the study looked at data from 1960 - 2005) the same couple would earn just 83% of the average. Conversely, couples in 1960 who had both done post-graduate work earned 176% of the mean household income, but that has grown to 219% in 2005. In short, the more educated are getting richer and the poor are getting poorer. At least education is getting cheaper so that future generations will have the same opportunity. Oh wait...
Pew Research Center has a nice write-up offering more details and what this all means.