Check out the latest design3 UDK tutorial, "UDK Racing Game - Level Design" here:
This Unreal Development Kit training module covers the level design and construction aspect of a downhill racing game project. Learn how to create and edit terrain, add static mesh objects, place lights and cameras, spawn vehicles, and more. Use UDK tools such as Kismet and Matinee to create simple connections and animations that help your level to function properly. Create a static mesh inside UDK and then export it to the modeling program, Sculptris, in order to create a highly detailed custom object. This is the first of two modules in the “UDK Racing Game” series.