I've written a MySQL script to migrate from a PostNuke database to a Drupal one.

Currently it migrates Themes, Users, Stories, Comments, Polls and Poll comments. These were the only tables which I was interested in. I wrote it to migrate Puntbarra.COM (the Catalan version of Slashdot) in early September.

It has been a bit complicated given the fact PostNuke database structure is horrible.

Take it from my sandbox.