File uploads

I like the new web-based upload tool that Flickr is using. I like it so much that I no longer use the Flickr iPhoto plugin. Update: there is a open-source project that matches most if not all the features of the Flickr uploaded: SWFUpload 2007.

One thing I could never understand is why don't browsers have a upload list with a progress bar? I mean, they have all the information they need to do it. Why haven't we seen that? Is there some technical limitation that I'm just not seeing?