The thought of using blogs in the classroom is an excellent idea.  It will give the students a voice in the classroom to speak about topics that are of concern to them that they might not want to say in the presence of others.  They can also read about others feelings about some of the same topics and get feedback or advice about the same things.
The only issue I have with it is that everyone will not have the common sense to be respectful of others and be able to give constructive criticism without being hurtful or hateful.