You're probably looking for the details of the whole Gallery PostNuke to Drupal conversion (including some of the pain Bharat went through with it). I'll get that written up in the next day or two. If you're a PostNuke person looking to transistion to Drupal, well, yeah, I'll get those details up, too.
You can contact me in the mean time, if you have specific Drupal/PostNuke/Gallery questions that I can answer.