One of the things that began my questioning of sermons (as the primary weekly tool of teaching and discipleship) began with a post I read on Jeremy Pryor's blog: http://jeremypryor.wordpress.com/2007/09/26/are-sermons-destroying-christianity/#comments
You'll notice, if you mosey on over there that Jeremy has removed his original post inasmuch as he didn't like the spirit of what he had written. I admire that. But there are plenty of interesting and worthwhile thoughts about sermons and sermonizing in the comments. I especially commend the extensive post by "Gavin" which gives much food for thought.