Now that I've jumped in with both feet and done lots of learning by trial and error, I'm finding the resources online that could have helped me. One community that has developed many support materials for educational blogging is ESL/EFL teachers. One great resource came from Creating and using weblogs in ESL/EFL. It takes you through the whole thought process of thinking through student blogs before you create them.
A similarly laid out resource focuses on Literature Circles and EduBlogs. Our fifth grade has a good literature circle process. Using blogs they could have lit circles with children in other schools in other parts of the world.