Make this Mac a server
If this Mac isn’t a server, you can make it one by install the Server app.
1. Buy the Server app from the Mac App Store. The Server app is installed automatically in your Applications folder.
2. Open the Server app and click Continue in the Welcome to Server window.
3. Enter the name and password of an administrator account on this Mac, and then click Continue to begin installing and setting up Lion Server software.
The Server app downloads the Server Essentials software package, installs it, and configures this Mac as a server
Its unclear how much Mac OS X Lion or this Server.app upgrade will cost. Hopefully, we’ll find out more at the WWDC keynote on Monday.
Mac OS X Lion Can Be Upgraded to Server With a Mac App Store Download