Johan Sörlin noted the Firefox trunk had an interesting development with new code being checked in for HTML5 drag and drop.
He told me:
I’ve fiddled some with the new drag drop support in FF 3.6 nightly. And I was amazed to find that you can get the plain/text and html/text contents out of the drop event. So in theory this can be used as a method of accessing the clipboard.
However this event doesn’t fire when you paste contents so it can’t be used for now.
This is good news because now we have drag and drop support in code, and hopefully soon we will have access to data on paste!