There are many benefits for students in blogging their work. When a student post work on the world wide web he is able to get feedback from so many minds, including fellow peers and professors from across the globe. Also, it inspires others on a much more broader scale so they effect of it can teach millions of people instead of hundreds or thousands. Thus, putting your work on a blog is like putting work up on a chalkboard and the internet is a classroom with millions of seats.
The Dear Kaia blog sparked the interest of a couple of U.S. teachers and classrooms and encouraged more involvement of parents with their child's learning.
Another example is the blog of Morgan Bayda. Her blog caught the attention of our teacher and this actually lead to a Skype discussion with her and our class where we learned about how a person just beginning their careerer in the education field values and uses technology to teach as well as learn.
In the NPR news blog, they educated people about the cautions of using Wkipedia as a credible source of research because of how easy it is for people to change it so its information favors a certain group's opinion instead of being completely factual.
Student blogging educates people outside the classroom while also obtaining feedback from millions of readers over the world. This creates a learning cycle that extends far beyond the limits of teh four wall classrooms.