iCloud document storage, and the biggest change to Open and Save dialog boxes in the 28-year history of the Mac. Mac App Store apps effectively have two modes for opening/saving documents: iCloud or the traditional local hierarchical file system. The traditional way is mostly unchanged from Lion (and, really, from all previous versions of Mac OS X). The iCloud way is visually distinctive: it looks like the iPad springboard — linen background, iOS-style one-level-only drag-one-on-top-of-another-to-create-one “folders”. It’s not a replacement of traditional Mac file management and organization. It’s a radically simplified alternative.
(Via Daring Fireball)