A recent Microsoft document came out, describing the changes in functionality
between Server 2008 and 2008 R2, showing there are serious changes.
For those of you not up to speed yet,
this is not like the 2003 to 2003 R2 upgrade, there are many core improvements in Server 2008 R2,
concerning Active Directory, GPO, NAP, Remote Desktop Services (not just a rename!), WDS, Powershell (has 2.0 included !),
just to name a few !
Download here: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=2db685c7-bb06-4083-9978-66b57661f6f7