Thefacebook reached my school in the second semester of my senior year. Although I haphazardly copied over my Orkut profile and added a bunch of friends, I never really got into it, having more pressing things to occupy my time.
However, noticing the steady stream of friend requests from people in younger classes, I was curious to see where it stood now. I was initially surprised by how many people in my year (2004) got around to signing up (perhaps they hadn't suffered social networking exhaustion like me). More shocking were the numbers that I saw when looking at the classes still enrolled in school. The class of 2008 has 84% of its members on Thefacebook, which is amazing when considering that this is a third party service with no endorsement whatsoever from the school. With such reach, I can see why some people get excited about the field.