Last month the W3C released a working draft of the File API, which
defines the basic representations for files, lists of files, errors raised by access to files, and programmatic ways to read files. The Firefox team have already implemented much of it, and have released a series of impressive demos on hacks.mozilla.org, which you can see if you have a recent beta of Firefox 3.6 (or a nightly trunk build).
The four demos shown to date display different (although related) aspects of the API, showing first multiple file uploads, then a drag and drop upload interface, next adding progress information (although this doesn’t work for me), then reading EXIF data from a JPEG image. You can imagine how these combined would be used for native drag and drop uploading to Flickr, for example.
The File API plays a big part in integrating the browser more tightly with the OS, particularly when combined with the drag and drop functionality, and I’m sure it’s only a matter of time until the other browsers implement this. Congratulations to the Firefox team for their work on this, and hacks.mozilla.org for some great demos.