I talked yesterday with the editor of a trade pub. They want to blog, but can only sell it to the publisher if the blog supports itself with ads. My advice: Go ahead and try. The ads likely won't bring in that much, but they won't know til they start. And by the time they begin analysing the blog revenues, they'll probably realize that the benefits of blogging stretch far beyond ads. (I have no idea, by the way, how much the ads on this site bring in, and in the church/state set-up we have here, it's not my role to ask.)
But even though blogging often makes good business sense, reports of a corporate boom may well be exaggerated. Debbie Weil trashes a survey that points to a rage in corporate blogging.