Hey Scott, you forgot Cactus in your article .... :)
For those interesting in testing J2EE applications, Cactus is a framework for unit testing server side java code. It is available at http://jakarta.apache.org/commons/cactus
and is part of the Jakarta Commons project from the Apache Software Foundation.
In it's current status, it lets you unit test Servlets and standard java classes that uses Servlet objects and simple JSP taglets. Work is under way to provide support for unit testing of EJBs and Servlet Filters. Check the goals and status web page for details at http://jakarta.apache.org/commons/cactus/goals.html
(it gives an overview of J2EE unit testing problems and how Cactus would solve them) and http://jakarta.apache.org/commons/Cactus/scope.html
(the scope page explains how to test the MVC model and gives the current status of Cactus in regards to this).
The goal of Cactus is to encompass as much as is physically possible the full spectrum of J2EE in order to provide unit testing for it.
Cactus is also very much XP oriented in that it provides custom Ant tasks and build scripts for major servlet engines in order to automate unit testing of J2EE applications, in the XP continuous integration fashion.