Using RichFaces in portlets would be great.
Julien Viet, of portal team, has just made the ajax capability in portlets.
see : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4035623#4035623
And for the rest :
From my try of RichFaces in JBoss Portal 2.4.1 :
DataTable does not work : it throw a :
when trying to cast the renderResponse from portal into a Http type class.
I will try the nightly build, if someone can say that some component may have yet been corrected.
and I will fill the wiki page JSFInPortletEnvironment with what is working and what not.