ADFS Solution using IAG
The CRM E2 team recently published a whitepaper that described how to use the Intelligent Application Gateway (IAG) for SSO/multi-factor auth scenarios. They spent a fair amount of time with the IAG team to ensure the web client scenario is well-covered and officially supported with IAG SP2. Let us know if you have additional questions after looking through the doc.
Implementing an ADFS Solution for Microsoft Dynamics CRM by Using IAG