I remade Quake 1 DM4 and DM6 for Quake 4 using the original source maps. The maps were scaled up slightly in all 3 dimensions to fit Quake 4 player height, and movement speed.
Pak file: http://www.fileplay.net/file/16499/quake1-map-pack-for-q4
I have not completely finished the lighting and grunge decals for DM6, but it is perfectly playable as is. I am not really a mapper, I just wanted to play these maps again, so I figured out how to do it :) The maps have visportals, and are player clipped, etc.
When scaling the maps, for example, the height between stairs was too high to walk up, so I used player clips in between the stairs (invisible stairs if you will) to reduce the height between stairs without having to change the viewable parts of the map.
I went with a space theme for DM4, feels like a space station, but still retains aspects of the original style texturing. The lava has been replaced with 'death by space'. I widened the lower platform to compensate for Q4 speed..it was too easy to fall off otherwise.
I realize the target audience for this is very small, few people still play Q4, and even fewer are old enough to remember these maps. I made them for my own enjoyment and thought I would share with anyone interested. With the exception of 3 textures in DM6, all textures are built in to (fully patched) Q4.
Comments and feedback welcomed and encouraged :)