Hi folks,
Mark Holmquist, Ankur Anand and others have been working on drag & drop uploading for Upload Wizard. You can see the current implementation on this test wiki (no SUL):
http://mwreview.wmflabs.org/wiki/index.php/Main_Page
We're currently doing an interaction and design review on it, and you're welcome to give feedback as well (note known issues):
https://www.mediawiki.org/wiki/UX_review_queue/Upload_Wizard_drag_%26_drop
Thanks, Erik