OK, Im an idiot. I had some jars in my classpath that were contaminating classpath (older jta stuff). However, I am stull getting errors. I can now do a lookup and get a $Proxy object that appears (looking at the debugger) to proxy the PersonSession class but I get a classCastException when casting it.
This ClassCastException problem was expained in http://www.jboss.com/index.html?module=bb&op=viewtopic&t=66651
You cannot have the interface classes in the webapp classpath. However, I am trying to run the whole thing in one VM under eclipse so I had to play around with separate trees for the ejb code to keep it out of the web-inf tree. It all seems to work now.