The reality of Blogs is that they will inevitably become just another marketing channel (victim). This has pros and cons. I think we're already seeing that Blogs are becoming less and less distinguishable from a website (so much so that it's hard to tell if you're looking at a Blog, Micro-Site or website... all of the above!).
Ultimately, what is a Blog? I think it goes back to what the first website was all about. It's simple. It's about publishing on the web.
Sure, we're giving Bloggers media accreditation to Presidential debates. Yes, Blogs are a credible and real force in the online world - I saw one research report that indicated a new Blog is created every five seconds. The question, as with all publishing, still remains: out of the millions and millions of them out there, how many Blogs are actually good, credible and interesting? Once you've figured that one out, take a step back and ask yourself the same question about all those websites?
Who's truly delivering on their brand promise? If you can't get it right offline, it's going to be even more difficult online and increasingly more so when you move into the Blog space.
As new and fresh as Blogs seem, they're powerless unless the person with the keyboard can keep the content fresh, relevant and human.