http://blogs.technet.com/mkleef/archive/2006/01/27/418194.aspxOne of Windows Server R2's cool things I think is Active Directory Federation Services (ADFS) and is based on the Web Services standard WS-Federation (PDF). Theres even third party tools that are supporting it now like Centrify's DirectControl which supporten-USCommunityServer 2.1 SP1 (Build: 61025.2)