Store uploads organized by username or other parameters

I know that the upload folder can be overridden in wp-config.php, but is there any way to store uploads so that the directory structure is based on username depending on who the author of the post is or other parameters? For example, I would like to keep uploads organized in this way:

wp-content/uploads/user1/image1.jpg
wp-content/uploads/user1/image2.jpg
wp-content/uploads/user2/image3.jpg
wp-content/uploads/user3/image4.jpg

I have searched for plugins and hacks but have not found anything that accomplishes what I want yet.