I've started playing with portlet 2.0 support in Struts 2, and the experimental JSR286 plugin currently supports both basic event and resource serving, which are two of the most anticipated features of the new portlet specification. In parallel, I've adapted the maven-jetty-pluto-embedded artifact to support Pluto 2.0, so I can easily develop and test directly with Maven or my IDE.
This is still very experimental, but feel free to give it a try. I've also created a very basic sample portlet that uses the plugin which you can check out and build. Note that you might have to build Pluto 2.0 from source unless you find it in a Maven repository somewhere.
Please drop me a line if you find anything that doesn't work, or if you want to discuss implementation and features.