Scott Allen puts it this way:
"A blog may become as important, if not more important, than your resume. The resume may get you onto the long list, but the blog is definitely a tool to get onto the short list. If you're trying to position yourself as an expert, then you should be blogging about your topic and building relationships with other people in your industry who are thinking about and talking about the same topic. And when I say you want to position yourself as an expert, I'm not talking about being a professional info-guru. If your business value is centered around your expertise on a particular topic, then you should be writing about it."