We have support for SSO scheduled for Seam 2.1.0.GA. I recommend you wait for this feature if possible.
Thanks for the reply - I'll look forward to that.
Having SSO support in Seam will be excellent and I'm also keen to see this.
However, for now if you still require some form of SSO to link between your apps, why don't you use encrypt the users data in your first app, then use a servlet to post this data to the other?