Yeah, definitely. It's a great way to keep track of things at school... if, say, I need to contact someone about a project, I facebook message them. I feel like saying hello to someone who I don't see every day, I write on their wall, etc.
Yeah, I have about 500 or so friends. Maybe 600, not sure. But is it a popularity contest? No. Everyone on there is either a friend from school, or from class, a friend from my past who I have looked up and reconnected with, someone from a club that I am in or running... all people who I could theoretically need to contact at some time, or who could need to contact me. It's only a popularity contest if you think it is.