There's a nice presentation by Frances Jacobson Harris called What's a Blog Doing In My Library? which goes through some basics of what blogs are about, including what some different types of people want from them. It also identifies some options for running blogs and gives examples. It was given at the AASL 12th National Conference.
http://www.uni.uiuc.edu/library/blogging/
(Photo by S. Webber: Bicycles, Sheffield University, November 2005)