This module was meant as a proof of concept and has been abandoned. Drupal 7 has vertical tabs out of the box (huzzah!), while the Vertical Tabs module provides vertical tabs for Drupal 6.
The node form has a lot of room for improvement in terms of usability. Based on work from the Usability group, this module was made to present different alternatives to how the node form is structured. Instead of merely looking at mockups and screenshots, we may now trial the suggestions to get a better understanding of how they work.
Please note that this is mainly a proof of concept, and not intended for use on production sites. It works only with the Garland and Minelli themes, not even a 100% at that. The Vertical Tabs module does vertical tabs a lot better.