I get a DNS error on http://www.kevinboone.com..., so it's a bit hard to guess what is going on, but from the error message i'd guess that you're using outdated configuration files. For simple beans, there is no need to change such settings, JBoss' default will do, so try to spot this configuration file that sets the container invoker (jboss.xml?...) and remove it from your ejb.jar.
Anyway i found another example that is working correctly. Well not exactly. I can deploy the jar but there is a problem with the client, with the jndi thing.
Does anyone have a really basic EJB example (Hello world like) working on JBoss. I cant find one really simple and thats is working correctly on google :/
By the way, i checked out the kevinboone thing and the problem is what i thought it would be: the container configuration is specified in the jboss.xml. This is not necessary, remove anything in the jboss.xml after </enterprise-beans> (except for the end tag of course ;-))