Reel Pictures offers web-based order fulfillment. This module allows the user to select an Ubercart order or order range and create an xml file to be uploaded to the service. The file gets wrapped in a zip for download (to prevent the browser from insisting on opening the xml file rather than downloading it).
At some point will have it hook the order process and offer the option of having it automatically create the file when the order is processed, but the service supports (and encourages) batched orders in one file, so creating a file on a single-order basis would defeat the purpose.
Haven't started a D7 version, but that will need to support UC3 and Commerce, I guess.
One issue is that there is code mapping in the xml generation between the UC shipper method codes and those supported by Reel. They don't support all of them (for example, USPS Parcel Post is not in there), so I'm not quite sure how to handle that, and whether the hard-coded mapping I have now will be insufficient for some reason, requiring an admin-panel mapping page.
The module is working. Just cleaning it up a little and will create the project.