Right on the Left Coast offers this philosophy on student blogs:
For the most part, I would like schools to focus more on what students do at school (get to class on time, act appropriately) than what they do outside of school (online activities, partying). If our schools spent more time on the 3 R's and less time on self-esteem, on wallowing in family issues, and on helping kids hide abortions from their parents, one would think that a lot more academic education would take place.
What kids put on their Myspace accounts is not the school's business--unless the students make it the school's business by threatening school personnel, by bragging about school vandalism, etc.
His sentiments are the same as mine, but note the tricky part about some content being something the school has a right to care about. Things like this always get tricky in the details.