I was on a hunt for what Longhorn will bring and found this document titled Changes in Functionality from Windows Server 2003 with SP1 to Windows Server Code Name "Longhorn" you can get it for your offline or online pleasure.

While I am mostly interested in PowerShell and IIS7 on Longhorn you can see from all the changes that there has been a huge investment in this release. I can even see me moving to Longhorn as my desktop OS soon.