Plupload-example is a project mainly written in JAVASCRIPT and RUBY, it's free.
A example Rails 3 app for multiple file uploads with Plupload
== Multiple file upload with Plupoad
This is an example of a Rails 3 app using Mongoid, Carrierwave and Plupload to do multiple file uploads.
I've written about this on my weblog [1].
[1] http://ikbenbitterzoet.com/2010/09/18/multiple-file-upload-with-plupload.html