Refer to the drag and drop API launched in API Version 11
http://developer.android.com/guide/topics/ui/drag-drop.html
A drag and drop operation starts when the user makes some gesture that you recognize as a signal to start dragging data. In response, your application tells the system that the drag is starting. The system calls back to your application to get a representation of the data being dragged. As the user's finger moves this representation (a "drag shadow") over the current layout, the system sends drag events to the drag event listener objects and drag event callback methods associated with the View objects in the layout. Once the user releases the drag shadow, the system ends the drag operation.