So I installed the Beta of Windows Server 2003 R2 which is:

“Try Windows Server 2003 R2, the update version of the award-winning Windows Server 2003 with Service Pack 1 (SP1), that extends your connectivity and control. “

…nothing new in the west – just an updated 2003 Server + several Resourcekits that ship with it.

Source: http://www.microsoft.com/windowsserver2003/r2/default.mspx