For example, if I see an app I like in the App Store, I can buy it and within a few moments that app is already on my iPhone, my iPads, and my various Macs. When I take a picture on my iPhone, by the time I fire up iPhoto on the Mac, it's already waiting in Photo Stream on all of my devices. iCloud makes living with multiple devices far easier because data is automatically dispensed across them all.
Last week, Apple CEO Tim Cook reaffirmed that iCloud is not a strategy with a specific shelf life, but a core part of all future Apple products, just as the Digital Media Hub strategy motivated Apple decisions over last dozen years or so. While iCloud integration on the Mac is not yet as comprehensive as it is in the iDevice lineup, Mountain Lion moves closer to real integration with Apple's online services.
The iCloud focus is apparent right away. After downloading and installing Mountain Lion, an iCloud login/sign up is one of the first things to greet you following a clean install. If you already have an iCloud account, your email, contacts, calendars, FaceTime info, Safari bookmarks and Reading List links are automatically configured. Once the Setup Assistant is complete, a virtual visit to the Mac App Store allows you to easily install any apps you've already bought.
With iCloud and a centralized location for app installs, you can be up and running on a new machine with far less effort than before. (More on this in a minute.)
More details on iCloud
Much of Mountain Lion's iCloud integration isn't new to Apple products, it's just implemented in a more refined way. For instance, updated applications will feature enhanced Open/Save options that now include iCloud. This allows documents created on one device to be automatically available on other devices for editing, viewing, or sharing. Before now, you saved documents on your desktop, then had to upload them to the cloud yourself, then go to the other devices and download them yourself.
OS X Mountain Lion looks much like its predecessor, Lion, though there's a new desktop wallpaper.
In Mountain Lion, the Open/Save dialogue box sports two options for saving: iCloud or On My Mac. When On My Mac is highlighted, a standard window allows for traditional file system navigation, Spotlight search and all other options you'd expect from a typical OS X Open/Save prompt. Selecting iCloud, however, replaces the file system window with the iOS linen background and large document icons. (It's similar to Pages on an iOS device.) From the large icon displays, you can flip through multi-page documents, and drag and drop documents onto other icons to create folders, just as you would on the iOS home screen.
If no documents are available, you can drag and drop documents to the Open/Save window to make them accessible via iCloud; they'll be moved from the Mac into iCloud automatically. You can also move documents to iCloud by clicking the little arrow next to a document's title, choosing Move To and selecting iCloud as the location. Just like that, your documents are available to any of your Apple devices with an internet connection.