One of the cooler features of Windows Longhorn Server is the Server Core role - Server core is a version of Longhorn without the GUI and all the stuff that comes along with a GUI. At first sight, it's a little scary to see a version of Windows with just a cmd.exe prompt. The tag line for server core has to be "the wow stops now!"
Andrew Mason, a superstar-Program Manager at Microsoft has setup of a Server Core blog - at http://blogs.technet.com/server%5Fcore/. The latest article in this blog is a useful description of what's new in Server Core for Beta 3.
About the biggest disappointment with Server Core is the absences of PowerShell. PowerShell is not supported since the .NET Framework is not installed on Server Core. This is more evidence that Server Core, a great idea, is still a little immature as a product. Hopefully the R2 version will support PowerShell and close this embarrassing loss of functionality!