This is really a dilemma, it is quite painful to drop such a cool feature, but after carefully consideration, I decided to take the move for the sake of simplicity:
Now the users can either upload the file locally or select the file in the incoming directory remotely(N/A); use Prev | Next to navigate, click the image to select the meta data, add tags by clicking(N/A). I consider that click need less effort for user to operate than DnD. And the Step statements directs the users but not enforce the order like wizard does.
It may be worthy to wrap the file browser as a dojo dijit, and that is also a good candidate for comet. The server may register handlers for file system events(check System.IO.FileSystemWatcher, inotify in Linux) , then push the status change to the client. That is quite a little work, so I would rather leave the placeholder here and implement some other features first.
This is r41, the save functionality is still broken, I would squeeze time to fix it ASAP.