One of Mountain Lion's most exciting features comes straight from iOS. If you're a mobile user, you're probably familiar with the "Share" button with its curved arrow shape. In iOS, you use this to redirect data to other apps. For example, you can tweet things, mail them, and so forth. In iOS 6, you'll be able to post them to your Facebook wall as well later this year.
Now this sharing capability has come to Mountain Lion. You'll be able to send links, documents, photos, and videos with just a click without having to drag your files around the way you used to. Click on the Share button and choose how you want to send a file. The share menu automatically presents those services that make sense in the context of the app you're using.
Each app is allowed to add its own services as well, so the menu you see is always application-appropriate. For example, in Safari, you'll be able to add bookmarks and save the current page to your reading list.
If you're worried about authentication, don't be. Once you've signed into your standard services (these include Twitter, Facebook, Vimeo, and Flickr), you can tweet, post, and upload with the sharing menu without having to worry about re-entering credentials. Mountain Lion provides system wide access to your account.
For many new Mac owners, your move to Mountain Lion represents your first major upgrade. To help users prepare to make the jump, Steve Sande and Erica Sadun wrote Getting Ready for Mountain Lion, an Amazon/iBooks eBook. It's aimed at first-time upgraders and people looking for hints and tips about smoothing the transition. We're sharing some of our tips on TUAW in a series of posts about the 10.8 upgrade. OS X Mountain Lion will be offered for sale in July 2012 for $19.99.