Personal documents are now in Amazon Cloud Drive
Documents will be delivered just as they have in the past and you will continue to have 5 GB of free cloud storage for your personal documents. Just "Send Once, Read Everywhere."
Documents stored in their native format
Also starting today, new documents that you save to the cloud with Send to Kindle will be stored in their native format (e.g. MS Word, TXT) so you can access them anywhere from Amazon Cloud Drive.