You really do have to be careful about what you put on the web, and making yourself unsearchable on Facebook is a good tool against stuff like this (of course, only if the searcher isn't your "friend"). I teach at a university, and one of my colleagues got a friend request from a student. The student missed a test because he was sick, and his Facebook updates made it quite clear which kind of sick he was. It was actually quite funny. I also know that a lot of school administrators troll Facebook for photos of students breaking laws or school regulations. In fact, I can think of a fraternity or two with revoked charters as a result Facebook shenanigans.
On one hand, you have to know better than to post potentially embarrassing photos or messages online, but it seems a little over-zealous for schools to seek out the ridiculous just to dole out punishment. But I guess some schools and employers feel that they have reputations to uphold, and if they can find it, so can anyone else.
