Often you find companies who want to use SharePoint to give their intranet users access to SAP resources. Recently I had to meet several business requirements to let domain users to a specific module in SAP Enterprise Portal.
In this particular requirement, users did no not want to use SharePoint as the main UI interface (web parts, page layouts, features, etc). They only wanted to to use SharePoint as a gateway into SAP. The issue was that if you just add a link in SharePoint into an SAP Enterprise Portal page via SSO.
For this particular requirement, the best solution was to enable SPNego on the Java stack on SAP and configure their web servers to accept SPNego tickets into SAP. The good news for our solution is that our SAP instance is also using Active Directory which made it simpler. Otherwise, the SAP team would have had to create a profile data store and map the Windows AD accounts to their SAP login.
I will post a few links that we found very useful for this task in my following blog post.