A major step in the evolution of the book:

Now you can go to the iTunes Store to buy the Kindle app from Amazon that lets you read ebooks made for the Kindle device on the iPhone. Yes, it's that confusing! Maybe they shouldn't have called the app the same name as the device...I thought "Kindle" was the device?

                               via  marginal revolution

No wonder people are confused. The book technology, as invented by Guttenberg, is going to be transformed from a physical thing into a digital media format with a variety of readers.The physical paper book will go the way clocks, maps, and calculators went: virtual ("ideal") application on a device of convenience.