
After releasing the second beta of iOS 7 for iPhone, iPad, and iPod touch developers, Apple has also seeded the second Developer Preview of OS X Mavericks to developers.

Mavericks includes features like a tabbed Finder, new full screen dual monitor capabilities, and Safari improvements. Developers can receive the update via the Software Update tool in the Mac App Store.
Article Link: Apple Releases OS X Mavericks Developer Preview 2