University Affairs has an article online about how students communicate. We're going through a lot of angst on campus about the best way to talk to the little buggers, who never quite seem to do what you expect. I know I never did either and nor did my peers, so we shouldn't be surprised that our children are taking after us.
The money quote in the article, I think, is here:

He adds that having prior contact with students increases the odds that they will actually read e-mails from his office. So he’s become a man of the people. “I try to ‘kick it’ with the kids,” he says. Dr. Laker has been getting out there and setting up meetings with various groups of students. He knows that it’s having an impact, as students have actually begun to e-mail him.

"He" being Jason Laker, Dean of Student Affairs at Queen's in Kingston.
I think we have a problem at Waterloo. Our administration - both faculty and non-faculty - seem remote and unapproachable. Queries to the Registrar's Office are usually handled fairly impersonally, judging by my own experience. Email is very unsatisfying, as you've no idea if the other person has even read it, but talking to somebody on the telephone who knows the answers is difficult too. Even applying can be frustrating, as we found out when my wife was applying to universities. (Waterloo screwed us with unclear requirements for mature students; I'd ask for my \$60 application fee back, but I know what it's like trying to get money from the RO.)
It's frustrating, because whatever lines we set up with students right now will have to be rebuilt in two or three years when something 'better' comes along, but increasingly universities are becoming prisoners of the free market, and lousy customer service - which is what we have, let's face it - is going to lose us customers. Eventually, it will rob us of our standing. We need to fix this.
I do find it funny that one of the reasons listed for IM being popular is this:

“Students really appreciated being able to talk with a real live person at the other end. That seems to add a level of personalization and authenticity that really appeals to students of this generation coming in,” says James Kim, director of communications for enrolment services at UBC.

I used to pick up a telephone when I wanted that. Navigating mazes of telephone menus can be annoying, but so is clicking through five different places on a website to find the customer service rep you need too, and multiple tiers always leads to misdirection and further frustration.
As an aside, I think email is one of the worst ways of communicating with students. I've ranted about it here at work. It's insecure. There's no way to know if the recipient has even seen it yet - I always ignore the little prompts when Thunderbird says "the sender has asked to be notified", and not all MUAs do that anyway. There's no way to know - short of annoying signing mechanisms like PGP - if the email really is from the person it claims to be from. Here, students are always running out of quota.
I don't have the answers, just lots of questions, unfortunately. If I had all the answers, I'd probably be a very rich man.