If you are still looking for one, I just released mine:
http://github.com/weixiyen/jquery-filedrop
Works for Firefox 3.6 right now. I decided not to do the Chrome hack for now and let Webkit catch up with FileReader() in the next versions of Safari and Chrome.
This plugin is future compatible.
FileReader() is the official standard over something like XHR.getAsBinary() which is deprecated according to mozilla.
It's also the only HTML5 desktop drag+drop plugin out there that I know of which allows you to send extra data along with the file, including data that can be calculated at the time of upload with a callback function.