At http://scn.sap.com/docs/DOC-40178 you will find some short tutorial videos that explain how to configure Kerberos based single sign-on for SAP GUI.
When using SAP Single Sign-On you can also benefit from enhancements we did to the configuration tools for SNC and SPNego:
- http://help.sap.com/saphelp_nwsso20/helpdata/en/af/cc55377253420dacc666da46a6f21a/frameset.htm describes the new transaction SNCWIZARD that automates the SNC and SPNego configuration
- http://help.sap.com/saphelp_nwsso20/helpdata/en/b0/b8359acbc74bfaba0425ee13460526/frameset.htm describes new capabilities in transaction KERBEROS that help you configure and validate the ABAP server configuration versus Active Directory
Best regards,
Christian