There are some great introductory tutorial on the Unreal Develompent Kit (UDK) by Simon from ShowMeThatAgain.com which were recently updated with some terrain editing and texturing tutorials. You can check out the site for the first few tutorial, however I wasn’t able to find links to the other, so I have provided direct links to those below.
http://www.showmethatagain.com/videos/UDK/intro/ : intro, setting up a new project
http://www.showmethatagain.com/videos/UDK/terrain01/ : large terrains in UDK from sat maps
http://www.showmethatagain.com/videos/UDK/terrain02/ : manual terrain editing
http://www.showmethatagain.com/videos/UDK/terrain03/ : creating terrain textures
http://www.showmethatagain.com/videos/UDK/terrain04/ : basic material creation and control
http://www.showmethatagain.com/videos/UDK/terrain05/ : blending between materials
http://www.showmethatagain.com/videos/UDK/terrain06/ : blending based on distance
http://www.showmethatagain.com/videos/UDK/terrain07/ : blending based on slope
http://www.showmethatagain.com/videos/UDK/terrain08/ : normal and detail maps
