pros & cons

pros:
--easy to include multimedia/links to online resources, powerpoint presentations, etc.
--open forum, students learn from one another
--students are published, engage in discussion with one another, have a product they can continue with after the class has ended, or as they travel
--compliments in-class discussion
--"slow motion" teaching
--always possible to edit, hide, or delete a post
--space for students to be very creative
--can publicize work with course material to a very wide audience, opens to a much wider community (ie, one student received replies to a question about the Seattle Opera from Seattle Opera representatives. Also, a google or google blog search for the term "Vienna 1900" now brings up a number of the blogs for the Vienna 1900 course).
--generally very user-friendly
--other applications: distance learning
--free

cons:
--very public (unless you elect to only allow invited individuals to see/comment on your blog: work with the "privacy settings" to create different degrees of openness)
-- can't critique posts quite as comprehensively
--lots of spelling/grammar mistakes
--(if used to replace journals) posts are shorter than many typical journal entries
--difficult to grade

other things to know:
--can de-center the class from the classroom