Yes, it is. You can point to any element inside a4j:repeat, rich:dataTable, rich:dataList :

 <a4j:poll id="p" reRender="text" interval="1000"
 enabled="#{timerBean.enabled}" action="#{listAction.timer}" />
 <rich:dataList id="list" var="data" value="#{repeatData.data}" >
 <h:panelGroup id="row">
 <h:outputText value="Row data :"/><h:outputText id="text" value="#{data.text}"/>
 </h:panelGroup>
 </rich:dataList>

In this case, content of the component "text" should be updated for a all rows.
Even, where is possible update some components for a selected rows :

 <a4j:poll id="p" reRender="text" interval="1000"
 enabled="#{timerBean.enabled}" action="#{listAction.timer}" />
 <rich:dataList id="list" var="data" value="#{repeatData.data}" ajaxKeys="#{listAction.keys}">
 <h:panelGroup id="row">
 <h:outputText value="Row data :"/><h:outputText id="text" value="#{data.text}"/>
 </h:panelGroup>
 </rich:dataList>

Rows numbers for update seted in a request-scope bean ( random number of rows in this simple case ):

/**
 * @author asmirnov
 *
 */
public class ListAction {

 private List data;

 private Set keys;

 /**
 * @return the data
 */
 public List getData() {
 return data;
 }

 /**
 * @param data the data to set
 */
 public void setData(List data) {
 this.data = data;
 }

 public Set getKeys(){
 return keys;
 }

 public String timer(){
 if(null != data){
 keys=new HashSet();
 int random = (int)(Math.random()*10.0);
 for(int i=0;i<random;i++){
 Bean bean = (Bean) data.get(i);
 bean.setText(bean.getText()+" X");
 keys.add(new Integer(i));
 }
 }
 return null;
 }


}

beans are defined in the faces-config.xml :

 <managed-bean>
 <managed-bean-name>repeatData</managed-bean-name>
 <managed-bean-class>org.ajax4jsf.RepeatData</managed-bean-class>
 <managed-bean-scope>session</managed-bean-scope>
 </managed-bean>
 <managed-bean>
 <managed-bean-name>listAction</managed-bean-name>
 <managed-bean-class>org.ajax4jsf.ListAction</managed-bean-class>
 <managed-bean-scope>request</managed-bean-scope>
 <managed-property>
 <property-name>data</property-name>
 <property-class>java.util.List</property-class>
 <value>#{repeatData.data}</value>
 </managed-property>
 </managed-bean>