A Blog originally was called a "Web-log" and was shortened to "Blog". Blogs started out in the 90s as website where people posted a journal online. Since then the Blogging phenomenon has included images, audio, video, applications, and collaborative blogging. But what is so powerful about a blog is that people can choose to view, subscribe (using XML code), comment, collaborate, and link to other posts. This interaction creates new communities where a fresh webbing of ideas, knowledge and friendship are being formed like never before. Below is a video of a book I highly recommend for any pastor interested in Blogging.
Recommended Reading - The Blogging Church by Brian Bailey