Hey Will,
What we need is basically a environment that will go into the skybox. Players won't be able to go onto the terragen terrain but it will be a great part of the environment and it will be in 3D and not just a 2D facade. We have some pictures of styles of surroundings that we would love to see. A must for these terrains is that they're flat in the middle though, since that's where the actual level will be. Eitherway, if you have some sort of instant messaging service it would be better communicating through that, since it's simply easier. I can PM you my IM details if you want, I use MSN and IRC.
Cheers,
Steven - DeV