This is as new to us as it is to many of you, and we spent a lot of emails back and forth in the tech department trying to figure out the best way to promote communication via blogs in the school district.
One comment from Dai Barnes on this post suggests that a good blog should be both informative and relevant. It should also be updated regularly, so your readers (if you have any) have a reason to come back. Most importantly, I think, is his suggestion that that blogging should encourage comments and collaboration.
Another commenter pointed to the Web 2.0 for Principals wiki site for other information. Some of their observations on school blogs are spot on in my opinion. Another good one to read is WordPress’s Introduction to Blogging page.
Then again, if you really want to know what blogs are good for, just ask a 4th grader.