Wikipedia Popular Among Educated and Wealthy
Pew Internet Project survey shows that Wikipedia is far more popular among the well-educated than it is among those with lower levels of education. For instance, 50% of those with at least a college degree consult the site, compared with 22% of those with a high school diploma. And 46% of those age 18 and older who are current full- or part-time students have used Wikipedia, compared with 36% of the overall internet population.
Most likely this is simply a function of Wikipedia being the most popular online reference site and college educated people are more likely to be intellectually curious enough to look things up than their less-educated counterparts rather than an increasing preference for Wikipedia per se. The study lists the top educational and reference sites:
There are no crosstabs given, though, so that we can how each of these breaks down demographically. My guess is that the education and income skews are even higher as one moves down the list to less search engine friendly sites.