So I finally decided to begin looking into writing a websphere 5 plugin, and I started by looking at the jsp source generated and much to my surprise it uses the same jasper engine tomcat 4.0.x uses.
Very cool, should be pretty easy now to start with the existing tomcat plugin code and mod it for websphere. I'm not entirely concerned about running an instance of WAS inside of IDEA. Attaching to an external WAS and debugging servlets AND JSPS would be more my cup of tea.
Hopefully I'll get the time to start on it soon, if not at least its out there for others to play with as well.