According to Boing Boing, some Amazon.com customers bought George Orwell's 1984 to read on their Kindles. The publisher changed their minds about offering a digital version, so the copies people had already bought were erased. I guess one of the features of a Kindle is that books you buy can be "unsold" to you and erased from your device.
Not owning/wanting a Kindle, I wouldn't really care if the book in question weren't 1984. One of the themes in that book is that when people can't access any tangible written historical record, we lose our collective memory. Is there any tangible evidence that these "unsold" books ever existed?