Kai's Mapping Tutorial is the only present WoP Mapping Tutorial. It's translated into both German and English (Altough the English version is a bit outdated for WoP 1.2, whilst the German version is updated for WoP 1.5, it's still mostly the same)
Here's the tutorial: http://wopmapping.chillerlan.net/ (Click British flag for English or German flag for German)
The latest version of Kai`s Mapping Tutorial can be found here: http://worldofpadman.net/editing_de (German)