I updated to 3.3.1 a week or so ago. I've been doing all of my work on the site in Firefox so I hadn't noticed this.
I went to test the site in IE 8 and IE 9 and neither of them will display the Drag and Drop interface when the Upload button is clicked. The Select Files button is grayed out, forcing me to click the browser upload link (which does work).
I've already attempted disabling all plugins and changing to the twenty-eleven theme. Neither made a difference. Both browsers were fully updated and running updated versions of flash, silverlight, java, etc.
Has anyone else encountered this before?
I'm nearing the point of handing this site off to the users that will be maintaining it, but I'd really like them to be able to upload media using the default method. These users will not be able to use a different browser, so I'd really like to sort this out.