Plupload is an open–source tool that allows you to provide uploading functionality for your website. So what makes it special? It utilizes HTML5, Gears, Silverlight, Flash, BrowserPlus or normal forms, providing some unique features such as upload progress, image resizing and chunked uploads—all this transparently and without the developer’s intervention.

This project is from the guys who made TinyMCE, so I’m sure incremental updates will be regular.