Apple has released OS X Mavericks Developer Preview 2 to registered developers. The update to the existing OS X 10.9 beta is versioned as 13A497d and is recommended for all users who are currently running the first version of OS X Mavericks Developer Preview.
OS X Mavericks Developer Preview 2 can be downloaded immediately through the Software Update menu and the Mac App Store.
As found in the App Store, the update weighs in around 1.5GB and is likely the fastest way to upgrade to the latest version. Those interested in making a USB install drive would need to re-download the installation client from the App Store. System requirements appear to be the same as the first developer release.
In addition to OS X Mavericks DP2, an update to Xcode 5 Developer Preview and a second dev preview release of OS X Server is also available.
OS X Mavericks is the next major release of Mac system software and includes over 200 new features and improvements, including tabbed Finder support, enhanced power management, and much more. Mavericks is due for a public release this fall, likely alongside iOS 7. Earlier today, Apple released iOS 7 beta 2.