I guess this is the first feature added since launch.
You now have Skyboxs which can be textured and are part of the background image.

The Skybox is found on the right Texture panel where you will find its texture and Hide/Show button(Skybox is hidden by default)

I have currently made it so the skybox texture is stretched across the entire camera and cannot be altered in any way(I see no reason a user would want to but as always let me know if I am wrong) 

I have also updated all the help files with the recent changes.