Being a teacher I am very careful what I do on the Internet. I am very worried that a student will get online and find me. I have a facebook page but have it so that only my friends can look at it. I am very careful who I add as a friend and what I put on the page.
The Internet can be a place for a future boss to look as well as students and parents. I would be really mad if an employer looked at one of my pages and didn't like the friends that I had on there or took a statement the wrong way, and in turn it affected my position or lack there of.
On the other had these sites are awesome for finding my old friends. I have found people I went to high school with that I would not have known anything about if it wasn't for the Internet.
I say be careful as a teacher. You always have to be aware that people are looking at you as a teacher, at school and away from school..
Good Luck Teachers:)