The coolest thing that I find with blogging is that you will get responses from the entire class. If I post a question for discussion, you'll get responses from even the shy kids in class where as if I had just asked that question opening for a class discussion, I would get the 5 or 6 students who always like share in front of the class.
Students can create their own blogs and they can read and respond to their classmates. This becomes a very engaging and interactive way for students to discuss ideas, topics and what they are learning.
Also, anytime the students are allowed to use the HP mini's in class they are excited. They just love technology.
There are many different blog sites available, but the best one by far, for the grade 5 & 6 setting would be KidBlog.
With KidBlog, you don't need an email account or gmail, and all of the comments need to be approved through moderation. This allows you to keep the blogging safe for your students.