I wanted to learn about drag and drop to a WPF application so I created this little demo. It's a simple app that accepts jpeg images and will display them when you drag files from windows explorer or photo gallery. It also shows a copy DragDropEffect and a nsupported effect whether the files are supported or not.
This msdn help article explains more about Drag and Drop support in WPF.
Source: http://blogs.vertigosoftware.com/files/alan/dragdropmedia.zip