If it were a very prestigious and high-volume blog where I know the owner isn't getting any $$ from the articles, I would probably do it. But, a very prestigious and high-volume blog that gets advertising money and whatever all else--you'd think that they'd be able to afford to pay the author, even if it's a tenth of a cent per hit or something like that. And if it's not prestigious and high volume, then huh? Why would this be worth a writer's time and effort?
The promotional opportunity here? Zilch. Again, if the blog owner hopes to build prestige and business through the blog, she should cut the writer in or, less painfully, cut them a check for a flat amount and have done.
Or maybe I should simply say yeah! What Ms. Hoy said!