Clustered sso does not work in the following use case:

1. start node1 and node2
2. hit webapp1 on node1 and login (FORM auth)
3. stop node1
4. start node1
5. hit webapp1 on node1 ... user is asked to login again (clustered sso failed)

I have noticed that if I hit another web application (webapp2 on node1) between steps 2 and 3, then clustered sso works fine.

I use this test case to verify that customers cluster environment is working correctly and to remove load balancer issues (sticky sessions, etc) from the equation.