But soon she felt too old for the social-networking site, and the customizable pages with music that were fun at first began to annoy her. By the time she graduated from the University of Puget Sound, Owens' classmates weren't on MySpace -- they were on Facebook.

Throughout graduate school and beyond, as her network began to expand, Owens ceased using MySpace altogether. Facebook had come to represent the whole of her social and professional universe.

"MySpace has one population, Facebook has another," said the 26-year-old, who works for an affordable-housing nonprofit in San Francisco, California. "Blue-collar, part-time workers might like the appeal of MySpace more -- it definitely depends on who you meet and what they use; that's what motivates people to join and stay interested."

Is there a class divide online? Research suggests yes. A recent study by market research firm Nielsen Claritas found that people in more affluent demographics are 25 percent more likely to be found friending on Facebook, while the less affluent are 37 percent more likely to connect on MySpace.

More specifically, almost 23 percent of Facebook users earn more than $100,000 a year, compared to slightly more than 16 percent of MySpace users. On the other end of the spectrum, 37 percent of MySpace members earn less than $50,000 annually, compared with about 28 percent of Facebook users.