Just warning everyone here, but I am about to get on a soapbox
To begin with I am not sure the issue here is "just" facebook, I think really while facebook might be the most common on campuses at the moment really the issue is with Facebook/ Myspace/ Friendster/ Livejournal/ etc. No matter how safe you think these sites are and how private you think the information you post on them is they are all sites that CAN be accessed by other people. All it takes is one "friend" to let someone see your page and your information is out there. Even if it's an innocent thing like leaving a computer logged in in the computer lab.
Also there was recently an article in the Triangle (Sigma's magazine) about how our EO views these sites and what requirements they have for them.
My opinion is simple here, assume what you post can be read by anyone. If you are not sure of something leave it off your page.
Btw there have been news stories recently (I heard one last week, sorry I can't remember where) of students in college trying to get internships and because of pics/ information posted on their facebook that a professor saw they were turned down for.
Okay off the soapbox... sorry folks!