Through the possible support for both an initial Claim-based Authentication (and the WS-Federation protocol), followed by a controlled protocol transition to Kerberos, through the use of Microsoft Windows Identity Foundation (WIF) 1.0, Microsoft Outlook Web Access (OWA) 2010 allows interoperability with major IDA market solutions. Through its support for the WS-Federation protocol among other OASIS standards, Microsoft Active Directory Federation Services 2.0 (AD FS 2.0) provides claims-based, cross-domain Web Single Sign-On (SSO) interoperability with non-Microsoft federation solutions.
Building on existing documentation, this step-by-step guide walks you through the setup of a basic lab deployment of AD FS 2.0 and OWA 2010 that exposes the OWA 2010 Web resource for cross-product, browser-based, federated collaboration. This document is intended for information technology (IT) professionals, and system architects who are interested in understanding the basic modes of interoperability between AD FS 2.0 and OWA 2010, and who want to create a lab environment for that purpose.
More Here
Courtesy:http://blogs.technet.com/b/rhalbheer/archive/2011/01/17/step-by-step-guide-exposing-owa-2010-with-ad-fs-2-0-to-other-organizations.aspx