This lab explores the idea of delegated service call via ActAs tokens: the exercise from the Web sites lab shows how to do that from an ASP.NET to a WCF backend, while the one from the WCF lab focuses on flowing identity info through a chain of services

calls.The first exercise of the WCF lab does not use an STS for authentication. It uses username & password credentials, and is designed to highlight the differences between the old WCF-only model and the enhanced model offered by WIF.

Labs from the Identity Developer Training Kit