This is the first quantification of the social network overlap problem that I've seen. How bad is it? Well, 64 percent of Facebook users also have MySpace accounts. Beyond Facebook and MySpace it drops sharply, with the sole exception of LinkedIn, which draws a lot of Ning and Plaxo users. I wish the survey had also included LiveJournal, which is often (inexplicably) left out of these social network comparisons, despite its millions of socially networked users. The original report is at Compete.