Just found this blog post today from Colin Moock on the new XML based file format (XFL) that will be available with Flash CS4. This is great news and since its XML based and not binary like FLA, I thinking this could make life easier for companies with big projects and lots of developers to manage versioning and merging of source files.

The XFL file is a .zip file which contains an XML file that describes the structure of the document and a folder with the document’s assets. Colin speculates that this separation of structure and assets will in theory allow you to edit the images of an XFL file directly in Photoshop without disturbing the timeline information also contained in that file!

Check out Colin’s Blog post for more info