The Patterns and Practices team have just completed a great reference about Claims based Identity. This coincides with the release of a number of technologies which make claims-based identity generally available to applications on the Windows platform. With the Windows Identity Framework (WIF), Active Directory Federation Services v2 (ADFS), the identity landscape has expanded, and the goal of the reference guide is to show how you can benefit by understanding these concepts and using certain tools.
The reference covers three around. These are WebSSO ( Web Single Sign on, Federation between applications which are not in the same trust boundaries and implementations for a Software as a Service architecture.
Details of the reference can be found at http://claimsid.codeplex.com/