Facebook may only be useful for looking up students and recent grads now, but those students will become the professionals of the future. I don't see those students abandoning Facebook when they have created a valuable social network.

It is the easiest way to find and keep in touch with friends and acquaintances whom you can't meet in person. (I've gotten in touch with a few friends from elementary school I haven't seen in 10 years through Facebook.)

And I definitely think it will become increasingly merged with professional networking. I've had potential employers friend me on Facebook, and a rather bizarre request from my current boss the other day. He wanted to "borrow" my account for 30 minutes to view the profile of applicants in my network. I turned down the request, but I couldn't help but be shaken over now how important Facebook has become in today's world.