Notice that I used a post-4.1 development build! So the above screenshot is an early version of what your Projects window will look like when you create plug-in modules in the next release of NetBeans IDE. For more information, see the draft version of the Quick Start Guide for NetBeans Plug-in Modules. (It is a work in progress, both the text and screenshots will change a lot in the coming months. Feedback on it is welcome!)
Next, I included the project above in the NetBeans sources (in the "serverplugins" folder) and then built the plug-in module, using an Ant script. I started the IDE and this is what my Runtime window looks like after I registered my new skeleton server:
Pretty cool, huh. Watch this space for an announcement of the tutorial that will explain everything that you need to know.