Hat tip to Bora at A Blog Around the Clock for this one.
The Michigan Daily has an excellent article written by Caitlin Schneider on the movement of University Professors to the blogosphere. Many articles have been written on the burgeoning importance of blogs in teaching, writing, and information dissemination. This one serves as a great primer, and its one I would highly recommend you pass on to potential employers (if your trying to get a job and have a blog, particularly in science) or to faculty that have yet to enter the blogging life.
It's also nice just to have that little push saying "yes - there really is a professional reason to do this - it's not just pure enjoyment."