I have tried to set up this plugin to get SSO on Jenkins.
We use it successfully with several applications already: Confluence, Jira, Subversion and Nexus.

But when I enabled this plugin, I get the log in screen every time I try to access Jenkins.
I get this when I already have a valid SSO session and can browse between the other SSO-enabled applications. But once I access Jenkins my SSO session is invalidated and I am logged out from all the other applications as well.

I can then log in to Jenkins, but the SSO session will not work in any of the other SSO-enabled application.

I see the following in the logs:
FINE: User is not logged in (anymore) via Crowd => logout user
Nov 29, 2011 5:41:53 PM de.theit.jenkins.crowd.CrowdRememberMeServices logout
FINE: Logout user and close SSO session
Nov 29, 2011 5:41:53 PM de.theit.jenkins.crowd.CrowdServletFilter doFilter

I can not see from the logs the reason that my session is being invalidated by this plugin, it would be nice with some extra log information.
It may have something to do with our setup, but this setup works fine with all the other applications;
All applications are using a separate subdomain e.g: jenkins.mydomain.com, confluence.mydomain.com, jira.mydomain.com