You can configure single sign-on through Access Gateway and through federation protocols.
Section 2.9.1, Configuring SSO to SharePoint Server
Section 2.9.2, Configuring a Protected Resource for Outlook Web Access
Section 2.9.3, Configuring a Protected Resource for a Novell Vibe 3.3 Server
Section 2.9.4, Configuring Access to the Filr Site through Access Manager