This module has been developed and tested with Ubercart 2.0.
Once enabled an administrator can define additional fields for billing and delivery addresses. Two additional panes will be available during checkout and order handling pages, with these extra fields.
With this module an administrator has a flexible way to define on the fly one or more field throught a simple interface located at admin/store/settings/checkout edit/extrafields. These fields will appear to customers during the checkout process and will be saved at end of this process on a separate database table for later use.
The module presents a new pane to display/change user input data in order view/edit pages. This pane visibilily is set on admin/store/settings/orders/edit/panes administration page.
This project is now on Drupal.org at http://drupal.org/project/uc_extra_fields_pane: please submit issues and bugs there.