I just stumbled across http://www.gamasutra.com/view/news/26382/Emergent_Incorporates_Sundog_Sky_Effects_Into_Gamebryo_LightSpeed.php Did a quick search and didn't find a topic about it.
Basically it's something about weather effects and such.
I thought this might be interesting as Bethesda might continue to use the Gamebryo engine for future projects, possibly TES V.
Here's a link:
http://www.gamasutra.com/view/news/26382/Emergent_Incorporates_Sundog_Sky_Effects_Into_Gamebryo_LightSpeed.php
Kind Regards