http://blogs.technet.com/server_core/rss.xml via http://blogs.technet.com/server_core/default.aspx

Server Core is a minimal server installation option for Windows Server "Longhorn". It runs a subset of the server roles included in Longhorn Server, specifically it supports the following:

• DHCP server
• File Server
• DNS server
• Active Directory

Server Core also includes the following optional features:

• Failover Cluster
• Network Load Balancing
• Multipath IO
• Removable Storage
• Bitlocker Drive Encryption
• Subsystem for UNIX-based applications
• Backup 

Server Core is all about letting an administrator run the above roles with less installed, running, and needing to be managed on a server. For example, there is no GUI shell on Server Core, the local interface for managing the server is the command prompt. You can use MMC snap-ins to remotely manage a Server Core installation. All of this provides the following benefits:

• Reduced maintance
• Reduced attack surface area
• Reduced management
• Less disk space required to install