Developers as can now download OS X Yosemite Developer Preview 6, which is identified as build 14A329f, from the Mac App Store. Separately, Apple's developer tools have also been given an update, with Xcode 6 beta 6 available to test.
Their release comes two weeks after the fifth betas were supplied.
People familiar with OS X Yosemite Developer Preview 6 say it comes with a number of new built-in wallpapers. Various system icons have been tweaked or changed as well, including in the System Preferences screen and battery icon in the taskbar. The new beta also adds a "Do Not Disturb" switch for Notification center.
Absent thus far from Monday's updates is a sixth beta of iOS 8. Previously, new betas for both Yosemite and iOS 8 were released side by side.
Apple has focused on what it calls "continuity" between OS X and iOS with its next major updates, as users will be able to seamlessly hand off content from their iPhone or their iPad to their Mac when within range. In addition, users will be able to answer and place calls or respond to text messages through Bluetooth connectivity to an iPhone.
Continuing betas for OS X Yosemite, but not iOS 8, may signal that the Mac software update could again arrive later than its iPhone and iPad counterparts, leaving users in the Apple ecosystem waiting to be able to utilize the continuity between both platforms. In recent years, OS X releases have arrived after iOS updates, but this year marked the first time that betas were issued on a consistent schedule for the two separate operating systems.