Now for the scholarly types, this community seems to be a bit more fragmented. I know many of these people who have accounts on myspace and even friendster, in addition to Facebook. I personally have an inactive friendster account that never ceases to amaze me when I get notices that someone actually was there. These are slowly dribbling off.
there are at least a few people from aoir that i've found on: tribe friendster facebook myspace linkedin ryze orkut [a site i've forgotten the name of...] and probably a significant number of other sites that i don't know about. I have friends from several different demographics on each of them. When folks try to compress a site into "teens go here" and "latinos mostly go here", they generally miss out on the fact that these sites are HUGE - so huge that there is a broad spectrum of behavior present on ALL of them. Surface-level characterizations are great, yes, but there's a lot of nuance in people's behaviors and networking patterns - that is easily missed. --elijah