At the last Seam webinar Gavin and Thomas said that they just made the necessary changes for Seam to work in the Portal. I believe the major changes were to integrate with the Portlet session and not specifically use an HttpServletRequest. I don't think they have posted a new release of Seam yet, so you will have to build Seam from source to try it. Also they said that facelets will not yet work but that is pretty high on their priority list. You can check out the webinar replay at http://jboss.com/services/online_education.
We are also very interested and tracking Portal / Seam integration. We are currently building portlets with JSF and EJB3, and really like the architecture.[/url]