At first before i watched that video i though blogging was stupid but now since i have seen the video i think it's pretty cool. It's a very good way to communicate with others and to give your opinion and get comments on it.
I think blogs would be useful for education by letting the kids have their own opinion about things especially if that child is quiet and shy during class. This gives them a way to express how they feel but not in front of a crowd of people.
I don't think blogging should be used in the classroom. It should be an "at home" assignment. It's wastes time in class because the kids need to learning. They should be taught how to blog first and then do the blogging assignment at home for homework.
You can use blogs and wikis to communicate with many people at one time. The kids can communicate with their classmates outside of class and share their ideas. They can communicate with kids from around the world that might be having trouble with the same things.
Jonassen, D., Howland, J., Marra, R. M., & Crismond, D. (2008). Meaningful Learning With Technology. Upper Saddle River, New Jersey: Pearson Prentice Hall.