Being friends with college students/work study students can be interesting. I got an e-mail from one of our work study students, calling off her whopping 2 hour shift. This after I monitored drunk Tweets the entire afternoon, evening, and morning of the day she called in "sick."
Another student, now a graduate, went on Facebook to complain about her dog chewing up her sex toy. With pictures. Of the dog and the apparatus in its mouth. She's friends with our Dean/Provost, many of her professors, the president of the college...and her photo albums can be publicly viewed. Good luck getting a job.

A former I.T. department co-worker ranted and complained about his new job for weeks on Twitter, Google+, and Facebook. All publicly available. He was fired shortly thereafter. Not only should he have been fired because of his online ranting, but I don't think I would want anyone working for me - in I.T. network security - that was dumb enough to post all that stuff out in the open.
It's funny how the social networks of choice change for the college age group. When I started here in 2007, it was all about Facebook. I joined Twitter in 2009, and very few students had heard of it or used it. We do an annual survey and it doubled from 15% to 33% usage from academic year 2010-11 to 2011-12. I'm sure it's higher on other campuses, but the jump was significant.