Promotional publishing. Traditional brochures have lost all credibility and value in this online world. And everyone has a blog; blogs are no longer differentiators. So, published books are the new blogs. Consultants can charge more if they have a book published. To be credible, the book would need a published price (preferably a high one), but all potential clients would get one for free. This is just an extension of blogging as an attention-getting tool.