JSI Tip 10184. Windows SharePoint Services and SharePoint Portal Server 2003 Support boundaries for Active Directory Federation Services.

Microsoft Knowledge Base Article 912492 contains the following summary and introduction:

SUMMARY

Active Directory Federation Services (ADFS) enables web single sign-on, federated identity and access management by securely sharing digital identity and entitlement rights across security and enterprise boundaries. The ADFS functionality becomes available in Windows Server 2003 R2.

INTRODUCTION

The purpose of this article is to describe supported configurations, known limitations, and recommendations for improving the user experience when you deploy Microsoft Windows SharePoint Services and Microsoft Office SharePoint Portal Server 2003 with ADFS.