WP uploader mod for uploading to user folders

Knowing that the standard uploader with WP only uploads files to one directory, is there a way I could hack/modify the uploader (preferably a plugin, though I’m flexible) to upload files from each WP author/user to separate directories that would belong to each constituent author?

Basically my site is a rather well-sized multi-user blog, where the users can upload a movie, piece of music, or picture and get it shown on the site, and to make managing files easier, I was wondering if there’s a way to divide each person’s stuff into their own directories/folders. I wouldn’t think this is really hard.

Any help on this appreciated. Thanks.