I've tested a ModCluster 1.0.3.GA with the load-demo.war, and it works; I've started a JMeter testcase with 200 threads, then I've stopped and started the one of the two AS node; I've undeployed in the node1 the load-demo.war, then I've deployed again the load-demo.war: not found any errors, it works, except some CacheManager NPE while the SessionCache is synchronizing:
14:16:28,261 ERROR [load-demo] Caught exception rolling back transaction
java.lang.NullPointerException
at org.jboss.web.tomcat.service.session.JBossCacheManager.loadSession(JBossCacheManager.java:1857)
at org.jboss.web.tomcat.service.session.JBossCacheManager.findSession(JBossCacheManager.java:489) ).

I've created a simple "echo" EJB with these annotations:
@MTOM
@Local
@WebService
@Stateless(mappedName = "hu.javaforum.modcluster.webservice.test.service.Test")
@LocalBinding(jndiBinding = "hu.javaforum.modcluster.webservice.test.service.Test")
@WebContext(contextRoot = "/ModCluster-test", urlPattern = "/service")
@SOAPBinding(style = SOAPBinding.Style.DOCUMENT, parameterStyle = SOAPBinding.ParameterStyle.WRAPPED)
public class TestBean implements Test
{

@Override
@TransactionAttribute(TransactionAttributeType.SUPPORTS)
public String process(@WebParam(name = "request") String request)

}

I've created a JAR, and I've deployed it to the cluster nodes, it works, I've started a JMeter and soapUI tests, it works.
Then I've undeployed this JAR in the node1, it works, all test passes.
Then I've deployed again (or redeploy) this JAR in the node1, and I've seen some HTTP/404 error in the reply:
HTTP Status 404 - /ModCluster-test/service
[...]
The requested resource (/ModCluster-test/service) is not available.

I've seen it in the httpd's access_log:
x.x.x.x - - [07/May/2010:14:26:20 +0200] "POST /ModCluster-test/service HTTP/1.1" 404 1056 "-" "Jakarta Commons-HttpClient/3.1"

And I've seen it in the access.log in the node1:
x.x.x.x - - [07/May/2010:14:26:20 +0200] "POST /ModCluster-test/service HTTP/1.1" 404 1056

It is bug?