Publishers HarperCollins and Simon & Schuster have signed a deal with Amazon to follow the agency pricing model for their books—the same deal publishers have with Apple for the iBookstore—allowing the two publishers to set their own books prices.
This means books will probably be the same price across Amazon's Kindle Store and Apple's iBookstore—more expensive than the $9.99 price Amazon loves in a lot of cases. The WSJ reports specifically "some new best sellers will be priced at $9.99 but most will be priced at $12.99 to $14.99." According to HarperCollins CEO Brian Murray, this deal has left his company's "digital future [...] more assured today than it was two months ago."
This leaves one publisher left standing from the five iPad megapublishers to renegotiate with Amazon, Penguin. It'll happen. [WSJ, Electronista]