You’ll find a brief description of the Windows server core installation of Windows Server 2008 at http://www.microsoft.com/windowsserver/WindowsServer2008/evaluation/overview.mspx. By the time you read this chapter, this page will probably be expanded or the URL will redirect you to somewhere that has a lot more content on the subject.
If you have access to the Windows Server 2008 beta program on Microsoft Connect (http://connect.microsoft.com), you can get some great documentation from there, including these:
Microsoft Windows Server Code Name 2008 Server Core Step-By-Step Guide
Live Meeting on Server Core
Live Chat on Server Core
There’s also a TechNet Forum where you can ask questions and help others trying out the Windows server ...