There is a good article up over at TechCrunch about the power of Blogs now that Twitter has somewhat made reaching out even easier, chipping away the authority of blogs 140 characters at a time. (And you have to see great response to the article by Tom Steinert-Threlkeld.)
My take is that blogging is blogging, and Tweeting is Tweeting. They have their respective values. In this 2.0 world, things change fast, but I do not see this as an evolution at all. Rather, blogs and Twitter should be used in an inclusive CRM 2.0 strategy. It would be ridiculous to value one of these over the other at this point. Both have unique values to your brand.