This post from Anne Davis of Edublog Insights is probably one of the most commented post on the subject of the use of blogging in education with 215 comments at the time of writing ( how's that's for engagement with an audience ).
I quote from her page:
"Blogging is educationally sound for teaching students because:
What do you think?
Is there anything missing?
If you want to find out more why not treat yourself to some online professional development