If you want to work on that, I can certainly help you. It is not part of the scope of 2.6.
However we are also looking at having RichFaces drag and drop component to work in a portlet env and leverage it for the page layout editor.
We are interested in something similar. Has anyone made any progress on this?
I am looking for this too..
Currently dashboard does support dnd and you can configure their positioning etc from Dashboard configuration page. It's not check/uncheck however.