there are still some issues concering seam+ portal http://wiki.jboss.org/wiki/Wiki.jsp?page=SeamPortlet.
On the other hand some stuff might work with seam 1.2.1
...but for seam2.0 (with ajax4jsf and richfaces) all portlet examples are gone :( http://www.jboss.com/index.html?module=bb&op=viewtopic&t=119038&postdays=0&postorder=asc&start=20
and here is the jira issue - please vote for it http://jira.jboss.com/jira/browse/JBSEAM-1585
...hope this helps...