The consumer collective has a version of Danny Brown's article on how the real value of a blog post lies in the comments. A blog should be a conversation starter - a social "aperitif" if you will - that sets the stage for the really valuable stuff: the reactions.
Absolutely true - a successful blog post is a catalyst for a discussion. A key consideration to making that happen is the voice of your post. Making sure that your brand voice and the audience of the blog post match is a crucial step. I am wary of brands who speak to youth in their "brand voice" - which sometimes has no resonance to the teens who are their target market.