I ran across an article in MSDN Magazine yesterday afternoon that sounds like something to try in SharePoint 2007. The scenario in the article talked about using ADFS for a Web Application to allow for Single Sign-On and better user management. I can think of some projects this could apply to. Has anyone tried this yet? I going to setup a test environment and see if I can get SharePoint 2007 to work with this.
The problem this could potentially solve is Host A has a Web Application and they have multiple partners(Client B, C, D, E, etc..) who want to use their Web Application and they want to authenticate from their home domain. This means no additional logins, no extra user accounts, and a trust relationship between the domains of Host A and Clients B, C, D, E, etc. A simplified example is shown in this picture below.
Single Sign-On - A Developer's Introduction To Active Directory Federation Services
http://msdn.microsoft.com/msdnmag/issues/06/11/SingleSignOn/default.aspx
Identity & Access Management - Simplify Single Sign-on Using ADFS
http://www.microsoft.com/technet/technetmag/issues/2006/07/Simplify/
Setting Up ADFS - Constructing a Lab Environment with Virtual PC
http://pluralsight.com/wiki/default.aspx/Keith/SettingUpADFS.html
Look for an update to this one later...