I completely missed the point of this article. What is it about weblogs that makes a blogger any different than any other content producer? If someone produces content that someone else is willing to pay for, then you have a professional. The choice of medium is irrelevant.
All of the examples in this article could be produced in numerous mediums (e.g., web pages, emails, newsgroups). Blogging may be a better medium, but there is nothing about blogging that makes the content any more valuable. If these companies felt that this information would be profitable, they would create the content.
People are not going to pay for a blog because it's a blog any more than they're going to pay for a book because it's a book. People pay for content. When professional content providers start using blogs as their communication medium then you'll have professional bloggers, but the fact that they use blogs will still be irrelevant.