Apple today released a candidate golden master version of OS X Yosemite to developers



From MacRumors:

OS X Yosemite brings a flatter, more modern look to OS X, with an emphasis on translucency and redesigned dock, windows, and more. It also includes a multitude of new features, such as improved integration with iOS 8 through Continuity, a new "Today" view in Notification Center that offers integration with third-party apps, a retooled Spotlight search with new data sources, and several new features for apps like Mail, Safari, and Messages. Over the course of the beta testing period, each Developer Preview has added new features and refined the look and performance of OS X Yosemite, although changes have become less obvious in more recent builds as Apple begins finalizing Yosemite ahead of its public release, which is expected in late October.

  Apple Releases OS X Yosemite Golden Master Candidate to Developers