Interesting. I tried this out. I really like the whole idea of collecting things in a block to have some sort of access to on an unrelated page. I noticed how you can use this to move menu items about, I'm just unsure why it would be more useful then the current drag-and-drop system in /admin/build/menu.
I tried this out by installing, enabling the Dropzone block on the right, going to /admin/build/, clicked the "Menu item Site building in navigation" radio that appears in the Dropzone, and clicked "Add". I then went to /admin/settings and clicked the button "Move below current item in navigation" and it was succesfully moved. Now you could get to /admin/build from within admin/settings. Then I tried moving it back and the order was out of whack, so that when I go to /admin, instead of seeing the "Site Building" on the right hand column, "Site configuration" is the first item on the right instead.
I cannot see any use for the "Path .." radio button.
If someone were to build a drag-and-drop interface for this, what sort of items would you be limited to using? If it was pretty much anything, images, node areas, or whatever... and the module gave you a block to keep multiple items, or a 'collection' of things, I could see a better use for this module.
I'm wondering what you envision this module better enabling someone to do?