KM vs Blog

       Davenport ask us to attention bloggers! More and more people began to write blog, and more and more companies began to deploy blog system as a knowledge management tools. What's the real relationship between blog and KM?
        Just as Davenport mentioned in his blog,

        It’s far easier to write a blog than to get anyone to read it.
        This imbalance leads me to believe that a couple of major changes need to take place in individual and organizational information environments.

         However, this is problem for blog, but not for KM system. A mature KM system already have good automated mining solutions. Compare a  blog system and  KM system on every aspect, you can find that  blog is realy much weaker than KM system to support  KM sharing  purpose. But why  blog  was so attractive?
         The key maybe the writing style and motivation. To write a blog, there's no big limitations, you can write everything as you want, don't need to care the keywork, the format, the statement organization, the higher leverl approval. And it seems that every blogger was motivated by himself to write blog. No pressure from others is needed.
           Thus the truth maybe: blog isn't a good KM system. Since it solved the hardest barrier of knowledge sharing, it becomes one option for KM. It's a remind to current KM tools provider, can current system provide a more freedom style for guys to contribute content?