I'm looking for approaches that people are using to allow single sign on between a variety of J2EE servers (I'm talking single sign on between web servers / applications).
Each vendor seems to have their own solution, but none of these interoperate nicely. What I would like to know is what people have done to enable Single Sign On between Tomcat and Domino or Tomcat and Exchange, for example.
Any insight would be appreciated.

Thanks,
Ray