Well, not exactly. While email and text messages are great at helping you keep in contact with people you know, I find Facebook is best at keeping me in contact with people I once knew or don't know very well.
For example, just last week I had an acquaintance who was potentially taking an internship in the city I moved to after I graduated college. This is an acquaintance that I haven't seen in over five years, and was never close with. The kind of person you'd be 100% never seeing again, since we had basically lost touch, minus the whole "we're Facebook friends" aspect.
Granted, I know one of the major gripes about Facebook on HN is that having a lot of friends on Facebook facilitates a lot of useless spam about people you don't quite care about. I totally understand this view.
But on the other hand, I learned that this acquaintance of mine might be stopping in the city I'm in, so far away from our hometown, and being the adult that I am and getting older and older by the minute, knowing just how hard it is to make and maintain friendships as you get older, I decided to give this acquaintance a call (on Facebook of course!) to see if they were free to meetup.