For the past year or so I've been working with the ADFS team to deploy 2 instances in our internal environment. The first scenario was to use ADFS to allow our North America based employees to use ADFS for single sign-on to our online company store. Without ADFS they needed to remember a seperate user name and password, with ADFS they are automatically logged in when on the corporate network, or can use their Windows credentials when accessing the website from the internet.
The second scenario was to provide some of our business partners access to Microsoft hosted websites using their Windows credentials. We configured a Sharepoint server and established federations with 4 of our business partners who would normally access these sites using accounts which we would provision in our extranet environment.
A Microsoft IT Value Card is a one-page overview of what an internal deployment looks like. It's a great way to get an overview of how we are using technology. There are several value cards available for download on Technet (click here). The ADFS card hasn't made it to the main page yet, but I just received the link so you can download it directly: http://download.microsoft.com/download/c/e/a/ceae784c-83fd-413a-a7da-0611c50a4e97/ADFS-R2ITVC.doc