Viewing American class divisions through Facebook and MySpace is an essay by Danah Boyd that's worth reading. She breaks down the socio-economic divisions she's detected, and it's quite interesting.
The goodie two shoes, jocks, athletes, or other "good" kids are now going to Facebook. These kids tend to come from families who emphasize education and going to college. They are part of what we'd call hegemonic society. They are primarily white, but not exclusively. They are in honors classes, looking forward to the prom, and live in a world dictated by after school activities.
MySpace is still home for Latino/Hispanic teens, immigrant teens, "burnouts," "alternative kids," "art fags," punks, emos, goths, gangstas, queer kids, and other kids who didn't play into the dominant high school popularity paradigm. These are kids whose parents didn't go to college, who are expected to get a job when they finish high school. These are the teens who plan to go into the military immediately after schools. Teens who are really into music or in a band are also on MySpace. MySpace has most of the kids who are socially ostracized at school because they are geeks, freaks, or queers.
In my ethnocentric mind I had the split based on age. Kids and teens were MySpace and then they matured and moved to Facebook. I didn't consider socio-economic factors.
The class system, it seems, even permeates our online meeting space.