You interview someone by e-mail. You write up the story and edit what they said, condensing their quotes to a few saliable points. Your story runs, and that’s that, you think. But to your surprise, your source decided to post all the interview questions and answers on their Weblog, showing the public that you cut something important to them.
A blog is only valuable if you can be brutally honest. I think that’s why tech execs have probably been the leaders so far. It’s pretty safe to talk in-depth on technologies.