Remove el-api.jar and el-impl.jar from your application.
In the Jboss 4.2 , there libraries provided by container.
Also, you can't use JSF JSP pages in the Jboss 4.2, as far as it contain Tomcat 5.5 container, but JSF requred Servlet 2.5 container.
The el-api.jar and el-impl.jar files are only in the ../default/lib directory. I presume they should stay in there. They are not in the application war file.
JSF/JSP seems to work ok for me in JBoss 4.2.1 I only have a problem when the application starts up after I add the richfaces jar files in the web-inf/lib and add the richfaces filter in the web.xml