Today I found public Friendster pages belonging to 2 of my friends from college. Neither of them has a Facebook page. Both of my friends had visited their Friendster pages in the last week.
This struck me as somewhat uncommon. I am under the impression that generally people in my cohort have at least a Facebook page, and THEN, possibly pages on other social networks.
For people younger than me, it is common to have at least a Myspace page, and then a Facebook page. (Sketchy older people might start with Myspace, too)
Both of my friends with Friendster pages have been members since 2003 - which is about when lots of people were on Friendster - but now they have started coming back.