Apple on Wednesday released OS X Mavericks Developer Preview 5. It's available for download through the Software Update system preference. It's the first update to Mavericks since Developer Preview 4 was released on July 22.
In customary fashion, Apple offered no public release notes for the new version, which intended solely for use by registered developers affiliated with Apple's Mac developer program.
Apple unveiled Mavericks to attendees of its Worldwide Developer Conference (WWDC) in June. The new version of the Mac operating system has new features like tabbed Finder windows, Maps, iBooks, new calendar features and a host of under-the-hood improvements aimed at improving power efficiency and performance.