James Dellow has posted a quote from Jim Vinson in his post Internal blogging is just one example of open information sharing inside an organisation that sums this up for me.
"In a recent discussion on the ACT-KM discussion list, someone mentioned that blogging is just one means of communication - that it isn't the be-all, end-all of knowledge sharing. I like this reminder because promoters tend to fall all over themselves with fantastic claims. On the other side, blogging provides a means of communication that people may need and don't currently have within their organization."
Just as a notebook has potential, but without anything in it, it's just a notebook, a blog has potential, but in reality it's just a platform, an enabler, it's what you do with it that matters.