Customers have asked me recently how you can implement Eclipse components that access arbitrary backend systems on behalf of users without requiring multiple authentications.
Lotus Expeditor has a feature called 'accounts framework' that allows you storing credentials to do SSO. It enables you to store, access, and use properties that are required to make a connection to, and communicate with, a local or remote service. This feature is already part of Lotus Expeditor 6.1. See here for an overview, the Java API doc and the extension point doc.
The credentials are stored in an encrpyted keystore (file) when using Lotus Expeditor. When using Lotus Notes 8.0 the credentials will be stored in the names.nsf.
In order to authenticate against any backend system login modules are used. To log into a remote server, you can implement your own login module and configuration or you can use one of the JAAS login modules provided by Lotus Expeditor.