Apple has issued a minor update to its OS X Server app for Mountain Lion, now at version 2.21. The $20 program allows anyone with a Mountain Lion install to turn the OS into a server OS utilizing a suite of utilities included in the application. The update improves the speed of downloading Mac App Store software through improved caching, adds Time Machine service monitoring, brings Retina display support for the Wiki Server, adds the ability to use Active Directory groups in Profile Manager and more.