At this morning's WWDC keynote in San Francisco, Apple announced the latest iteration of OS X, Mavericks, which features a new tabbed finder, independent handling of multiple displays, tagging, and a Safari redesign.
While developers can get immediate access to Mavericks, the general public will need to wait for the software's official release, which is expected to take place in the fall.
Article Link: Apple Gives Developers Access to OS X Mavericks