Apparently the publisher changed its mind about offering an electronic edition and Amazon sided with the publisher and angered their Kindle ebook customers.
According to the NYTimes: "An Amazon spokesman, Drew Herdener, said in an e-mail message that the books were added to the Kindle store by a company that did not have rights to them, using a self-service function. ?When we were notified of this by the rights holder, we removed the illegal copies from our systems and from customers? devices, and refunded customers,? he said."
This is really scary for most Amazon ebook buyers because they didn't know that Amazon had the technical ability to delete the books they have published, nor the right to do so. According to the Times "Amazon appears to have deleted other purchased e-books from Kindles recently. Customers commenting on Web forums reported the disappearance of digital editions of the Harry Potter books and the novels of Ayn Rand over similar issues."
Read the whole story on NYT. This is unbelievable!