Aaron over at Digital Leadership Network wrote a great post on the different kinds of blogs and then gives some suggestions on why and how your church should blog. I'm summarize his comments below.
What Kinds Blogs Are on the Web?
1) Expert/Personality - an expert or big name giving you advice
2) Personal - someone sharing what they did that day [pictures, journaling, etc.]
3) News/Information - group of people who share information [ex- Church2.0]
4) Humor - just for fun
Suggestions for the Blogging Church:
The biggest keys to blogging is consistent updates. My suggestion would be to take the team blog approach, with different people taking on different roles. You can easily offer up separate RSS feeds or pages to break down the blogging into the three areas above:
The Expert Blog: The pastor, of course. If the community is interested in engaging in thinking about the message series throughout the week, the pastor could/should post ideas and thoughts that continue (or set up) Sunday's message.
The Personal Blog: Other leaders in your church? Perhaps small group leaders can use a public church blog to toss information and thoughts around to their attendees. A small group can open up to any curious visitor to your church's website using blogs.
The Information Blog: If a church's blog was consistently updated with upcoming events, prayer needs, updates on church member issues (ex- announcements) it would be a great chance for church members to feel loved and want to interact with the site.