Random House said in a brief statement Monday that it has agreed to the "agency model for e-book sales," according to AppleInsider. That agency model had been the chief stumbling block keeping Random House books from joining the iBookstore.
In the traditional publishing model, retailers bought books from publishers at a discount price. Then those retailers sold the books to customers at a markup, with that margin being the retailers' profit. In the agency model, e-books are sold to the customer, and the revenue is split between the retailer and the publisher. Because the agency selling the books (in this case, Apple) set the price, Random House had been concerned the model could significantly decrease profits.