I'm working on a SharePoint portal site, while user should be redirected to it from SAP Portal, both of the two portal, user is going to be authenticated through Active Directory.
So is there a way to have a single sign on for both of them, so user login to SAP portal and then be redirected to Sharepoint portal without providing his login credentials again?
I'm not an expert on this area (and definitively not one on SAP) but if your SAP Portal and your SharePoint are set-up using the same authentication mechanism (eg : ntml or Kerberos) and you have windows authentication, this should be transparent (assuming the current user is member of any group of SharePoint that has at least a read access).
One of the client I had been working with had a similar scenario, a SAP Portal, several SharePoint site collections and share authentication across them, but there were relying on a dedicated SSO solution from Novell.
This forum discussion seems to cover a similar requirement