One of my favorite parts of the announcement is this bit:
“Normally, making margin notes in library books is a big no-no. But we’re extending our Whispersync technology so that you can highlight and add margin notes to Kindle books you check out from your local library. Your notes will not show up when the next patron checks out the book. But if you check out the book again, or subsequently buy it, your notes will be there just as you left them, perfectly Whispersynced.”
Try doing that with a paper book. But seriously, this is just the sort of innovation a new technology ought to add, making it a valuable alternative to previous technologies—not necessarily a replacement for them.