I just passed a milestone: I just had my first experience where I desperately needed an answer and search pointed me right to a blog entry that immediately answered it. In my case, I needed to know the amd64 calling convention, and MSN search pointed me to an excellent blog post by Raymond Chen that described exactly what I needed to know, and did so in a very concise clear way. It's such a wonderful feeling when you can get an answer like that so quickly and it turns out to be so simple.
In one sense, I actually prefer blogs (from reputable sources, of course) to official references. Whereas technical references may have a lot more jargon, may even be wrong or out of date, and rarely emphasize the danger cases in an intuitive way. I find the good blogs are accurate and not only present the information, but focus on the key issues and explicitly call out gotchas. It's the best of both worlds when the blog actually links to the technical reference, just in case you want to double check the facts.