In part, the article reads, "[P]ublishers focus much more attention on the hardcover release. As they prepare to introduce a book, any combination of timing, packaging, marketing and other factors could help ignite the mysterious spark that leads to best-sellerdom. Contributing to the success of “The Secret,” for example, could be any or all of the following: the subject, the title, the initial DVD release, the marketing campaign, the power of the Internet, “Oprah” and the latest trend."
What's interesting is the article acts like $40K is a sad, pitiful advance, and I've known authors who have gotten far less than that.
Read more here.