There was a time when installing and configuring Mac OS Server or OS X Server was no modest undertaking; it was an entirely different operating system build, requiring a reinstall or upgrade to get at the yummy workgroup nougat center of Apple's desktop system.
Those days, thankfully, are gone: OS X Server now exists as an application shim on top of regular ol' OS X, and you can buy it in the Mac App Store for just $19.99. (It used to be considerably more expensive, especially if you wanted to run it on the purpose-built hardware.)
The latest edition of the OS X Server package, OS X Server 3.0, is the build tuned to work with OS X 10.9 Mavericks. As of this evening, it's showing up in the Mac App Store for download or purchase. Among the appealing features of the new OS X Server build (profile management with VPP app distribution, free XSan, the new XCode build server, and the much-loved file and web serving tools) is a revamped Caching Server, which saves Apple software updates -- both Mac and iOS -- to local storage, minimizing the impact to your company bandwidth.
If you're updating a machine to OS X Server, let us know how it goes.
[hat tip to iMore]