Went to stand up Office 2010 KMS server on an existing 2008 server.  I went to install Office 2010 key management host and I get “Unsupported Operating System”.  So I decided to install on 2003 license server again already existing and I get the same error.  I run the key management host on my windows 7 computer thinking maybe I received a bad download runs with no issues.  So after some digging threw office 2010 beta and official release documentation and a few Google searches I found out some very interesting information.  Office 2010 KMS only runs on Windows 2003, Windows 2008 R2 and Windows 7 all other operating systems are not supported.  Microsoft has released a patch to help those still running 2003 KMS server.  But so far no patch for the 2008 server the only fix I have found for that is to upgrade to R2.