I found a great File Upload plugin for jQuery. It uses JavaScript + Flash to support multiple uploads and progress reporting (similar to YUI and other multiple file uploaders). From the plugin’s author:

This plugin allows you to change any element with an ID on your page into a single or multiple file upload tool. The plugin uses a mix of JQuery, Flash, and a backend upload script of your choice to send files from your local computer to your website server.

My preliminary review has yielded excellent results, and this is much easier to implement than the YUI Uploader, SWFUPload, and some others I’ve worked with.