On Friday the New York Times reported that Animal Farm and 1984 both vanish from Amazon's Kindle machine but it seems that copyright is the problem.
According to the paper
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.