If you need to configure ADFS v. 2.0 for use in Claims-based authentication scenarios, interestingly enough, ADFS v. 2.0 DOES NOT come pre-installed with Windows Server 2008 R2--even after the release of SP1.
Therefore, you will not be able to install ADFS as part of the Server Roles that come with Server Manager. Instead, you will have to separately download the release of ADFS v. 2.0 and install and configure it separately.
You can download the release of ADFS v. 2.0 from here: http://www.microsoft.com/download/en/details.aspx?id=10909
There is also an update rollup for ADFS v. 2.0 available which can be downloaded from here: http://support.microsoft.com/kb/2607496
In addition, this is an excellent article on configuring ADFS v. 2.0: http://www.sysadminsblog.com/microsoft/installing-and-configuring-adfs-2-0/
Therefore, you will not be able to install ADFS as part of the Server Roles that come with Server Manager. Instead, you will have to separately download the release of ADFS v. 2.0 and install and configure it separately.
You can download the release of ADFS v. 2.0 from here: http://www.microsoft.com/download/en/details.aspx?id=10909
There is also an update rollup for ADFS v. 2.0 available which can be downloaded from here: http://support.microsoft.com/kb/2607496
In addition, this is an excellent article on configuring ADFS v. 2.0: http://www.sysadminsblog.com/microsoft/installing-and-configuring-adfs-2-0/