The BlenderArt magazine has a new issue released just a couple of days ago, and there is a particular article at the magazine that could be of interest for most architectural visualization artists using Blender. This article was written by Miroslav Horvath and is about terrain modeling with Blender. The article is about the tools we have in Blender to model terrains like displacement maps, sculpt mode and others.
This is a free electronic only magazine that only talks about Blender, which from time to time publishes a few articles related with Blender for architecture. If you want to read the article, just visit the BlenderArt Magazine web page and download issue 39.