Me and Mark played a bit on multiplayer, and we found a small discrepancy. On my computer, there was rain, but Mark's did not have rain. I would not really call this a bug; this is why I called it a discrepancy.
This was using beta-2 on Windows Vista.
//EDIT
Tried out the new map editor. It is nice, but I am wondering: is anything besides menus changed?
Also, how is the g3d viewer different?