Long ago something sort of similar went down (back when there was FAR more SS2 FM makers around), where we all did 1 room to a level, in a rotating fashion. Started out well, but then slowly died off unfortunately.
I have an idea for a Map Jam that the SS2 mapping community could participate in. I think we've all played SS2 so much that we can basically sleepwalk through most of the game. During my playthroughs, I can get from the start to engineering within an hour or two. What if there was a map jam in which there war new custom redesigned maps for each deck, they could be bigger, more challenging, filled with immersive details, whatever, as long as it stays with SS2's overall plot. I really want myself and others to feel like we're experiencing SS2 for the first time again. After seeing the amazing things that can be done with the dark engine as demonstrated by Thief: The Black Parade, I'd really love to see what this community can do.