yeah most games avoid it like DoD:Source (and non source) for example, its simply avoiding an argument. very little is changed but it saves ALOT of problems
the 2-sided materials check-mark in the mateditor? that one doesn't work in direct3d viewports but for example if you set your display driver to open-gl.
For a practical example, you can take a look at Glen Southern's Minotaur - Part VI, even if it is for Silo, it applies to any other poly modeling software.
http://udn.epicgames.com/Three/ProceduralBuildings.html most of it might not apply, but I think the pics do a good example showing how building can be broken up.
I had a little fun with this today. The one thing that really stood out to me was the AMAZING performance. And this fantastic forest level they had as an example...it was great!
Yeah, there is only one wireframe shot of an environment there, and even that is an in game screenshot. I am hoping to see actual high poly source model example.
Don't bother with that! Pick up a good reference photo or texture, and copy it. It's all in your eye! Great example Suffeli. It's like, an organic texturing 101!