We have not implemented the feature yet because it was not with a high popularity and we find out that there a some unclear moments. What exactly do you want to happen when the file is uploaded and saved? By that time the ProgressBar would already have reached 100% completion.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed