Inside OS X 10.8 Mountain Lion: Share Sheets put AirDrop, Twitter, Vimeo sharing everywhereShare Sheet icons throughout OS X Mountain Lion make it easy to share documents via AirDrop, Twitter, Mail, Messages, Flickr or Vimeo, and perform other context sensitive shortcut actions, such as setting an account picture
Apple introduced AirDrop in OS X Lion, making it easy to set up a secure, configuration free file sharing session between two Macs on the same network. In Mountain Lion, Apple makes the feature accessible all over through the new Share Sheets feature.
Share Sheets present a "send" icon familiar to iOS users in a variety of places throughout OS X Mountain Lion, from Quick Look panels to Open File dialogs to Contacts, Safari and Photo Booth.
Clicking on a Share Sheet icon opens a menu displaying a variety of contextually relevant sharing options based on the accounts configured in the "Mail Contacts & Calendars" pane of System Preferences.
Quick Look an image, for example, and Share Sheets present options to send via Email, Message, Twitter, AirDrop or Flickr.
Quick Look a video, and the options change to support Vimeo (but not Google's YouTube, a telling example of the crumbling relationship Apple has with the company. Five years ago, YouTube was the primary video sharing service supported on iPhone.)
AirDrop a file and Share Sheets presents a dialog that searches for nearby Macs with an AirDrop window open in the Finder.
Once a local AirDrop user is discovered, the panel presents the ability to send the selected file to the other user, working just like AirDrop from the Finder.
Twitter presents a similar panel, also derived from the tweeting user interface of iOS, showing a character count and allowing you to add your current location to the tweet if desired. (Again, notably absent from Sharing Sheets is Facebook integration).
Special Share Sheet options are presented by other apps. For example, Photo Booth allows you to select a snapshot and perform typical graphic sharing options as well as options to Add to iPhoto, Set Buddy Picture, Set Account Picture, or Change Twitter Profile Picture.
From Safari, the new toolbar Share Sheet icon offers to Add to Reading List or Add Bookmark, as well as Email, Message or share via Twitter.
Developers familiar with Apple's Sharing Sheets feature noted that the feature is based on a new Sharing Service API, which allows apps to create their own custom user interface for sharing content through the available services configured by the user (such as Twitter). Developers reportedly can also create their own custom services, opening the potential for Facebook, Google, Yahoo, Microsoft and others to define links to their own photo, video and document sharing services.