A file uploader for Backbone using cmlenz jquery-iframe-transport's implementation of the iframe method for cross-browser support.
There's an example on the demo directory. It includes a Backbone app to handle file uploads, show them on a list and delete them.
It also provides a simple sinatra app to act as a backend for your uploaded files. To run it, execute ruby file-upload.rb on demo/ and go to http://localhost:4567 on your browser. You may have to install sinatra per gem install sinatra first.