Wow. Does that river actually cross the same mountain range 3 times? I think we're going to call out the River National Guard for that one.

Anyway, battlemats in Photoshop. A battlemat is much like a dungeon map: you need a grid, texture, and objects. I recommend starting with Duvik's dungeon tutorial in our Tutorials section, and then hit the Dundjinni user creations forums and cgtextures.com for textures and objects.

Also, check out Dorpond's tutorials, which cover some shadow techniques and battlemat-scale terrain building in PS: http://forums.rptools.net/viewtopic.php?t=2142