I\'m currently developing a web file browser using jquery and php. One of my sub-tasks is to be able to select a couple of files/folders and drop them into another folder.
How about http://www.myphpetc.com/2009/11/jquery-ui-multiple-draggable-plugin.html
This is by far the simplest solution that I've found to a multi-item drag and drop. It's by brianpeiris. He created a demo of it here in answer to the stackoverflow question grouping draggable objects with jquery-ui draggable. I just wish that I'd found it before I found all the other solutions.