seem to have resolved their issues. An Amazon customer quotes the WSJ:
Amazon.com Inc. and Pearson PLC's Penguin Group (USA) have resolved their differences over the book-pricing model that enables publishers to set their own retail prices.
As a result, Penguin is once again making its new titles available to Amazon in the digital format. Penguin had halted the delivery of new titles in the digital format as of April 1. An estimated 150 titles were affected.
"Our differences have been resolved, and a full selection of Penguin books will be available on the Kindle," Amazon's electronic-book reader, said David Shanks, CEO of Penguin Group (USA.)