According to reports, Apple's emphasis at this year's WWDC, which is happening in a month's time, will be on OS X 10.10. The new version of OS X is reported to feature an "end-to-end redesign" that will bring it in-line with the look and feel of iOS 7. In fact, reports are suggesting that the scope of changes will not be unlike that of iOS 7.
OS X 10.10 is currently said to feature similar toggle designs to iOS 7, sharper window corners, more defined icons and more white space. However, users who are concerned that Apple is trying to merge both OS X and iOS should breathe easy as the company has said many times in the past that they see the two OSes as separate entities.
With WWDC just a month away, it is also reported that Apple is pulling iOS user interface developers over to the OS X team to finish the new design for WWDC.
Source: 9to5 Mac