Jitspoe posted a screenshot a while back (about a year ago I think) of a level designed in 3DS for some other game, I remember being really impressed by it.
You can sort of replicate the process at the moment, ViciouZ and I found the best way to do this now is to model the maps in Blender/3DS Max, export as a Q3 Map, run through the Q3 -> Q2 map exporter (I forget the author) then touch up and compile in BSP.
However, I personally feel this topic should be merged with 'New Map Format'...