Attached is the file we use for the JBoss5 client jars when conecting to a JBoss5 server (remote EJB) from a JBoss7.1 client.
Also, in our jboss-deployment-structure.xml file we exclude both "org.picketbox" and "org.jboss.logging" in order for this to work.
Since I cannot figure out how to upload more than 1 attachment, here is the jboss-deployment-structure.xml file for one of our projects:
<!-- exclusions to allow connecting to JBoss5 clients -->
So far we haven't run into any problems, but you may need to be careful about the things you add to your dependencies list too.
So far, I do not know how to connect to a JBoss7.1 server from JBoss5