Apple has released updated versions of the Keynote, Pages and Numbers iOS apps, adding support for iCloud's Documents in the Cloud feature. iCloud now backs up documents automatically and syncs versions between the iWork apps on iOS and the Mac.
OS X Mountain Lion is required to sync documents between the Mac and iOS versions of Keynote, Numbers and Pages.
Keynote/Numbers/Pages 1.6.1 works with iCloud to make presentations automatically available between your iOS device and Keynote on your Mac*. Changes made to a presentation on one device are instantly available on the other.
*Requires Keynote 5.2 or later installed on OS X Mountain Lion
Apple has been working on removing the hierarchical file system for several years, something that should make finding files easier for computer novices. Apple's marketing specifically highlights this as a feature: "You don’t have to manage your documents in a complicated file system or remember to save them to a special folder."