The jmx datacontrol is a new feature of adf. This datacontrol is an interface between the jmx servers and adf. Now you can make a gui on the mbean attributes and operations. In jdeveloper technical 2 preview you can only make a jmx datacontrol. You can't configure it, you have to do it manually but there is no information how to do that. But if you look at the dc-adapters.jar ( this is the datacontrols jar ) You can open the jmx schema. Here we see dat de jmx datacontrol allows you to connect to mbeans servers and give a interface to the attributes and operations of this mbean server.
This datacontrol makes it possible to make a frontend on the mbeans in your own applications. In 10.1.3 you had to go to em website. I think this gives jmx a boost in jdeveloper 11g applications.
Here you see the schema of the jmx datacontrol