Thought I'd post this little snippet, as it wasn't the most intuitive thing to come by... If you pass a parameter from a link on one of your pages, and you want to reference the value of that parameter inside pages.xml, do the following (using the param object was the key):

Link on the page:

<s:link styleClass="MenuOptionText" value="#{item.label}" action="redirectToUri">
<f:param name="targetUri" value="http://labs.jboss.com/jbossrichfaces/"/>
</s:link>

pages.xml:

<rule if-outcome="redirectToUri">
<end-conversation before-redirect="true"/>
<redirect view-id="/uriSelectionRedirector.xhtml">
           <param name="targetUri" value="#{param.targetUri}"/>
</redirect>
</rule>