Two benefits I thought of concerning facebook was if you wanted to get a message to students, they would see it faster if you put in on their facebook rather than send an email.
Also I helped a guy in special collections Wednesday and he wanted to look at old yearbooks (1988-1992) to get some names of baseball players to try to get together with them next year. It made me think that if they all had facebook, he could probably get in tough with them and immediately be able to get a message to them.