They clearly state that it's not a mod. The whole thing is powered by redstone and spawners. It looks really fun, despite the potential lag issues.
Once we update and all of the schematic importing is complete, I imagine that we'll be looking for alternate world choices. I'd really like to play this on the server, but one thing does bother me: the fact that the game drops so much loot. As a stand-alone world, it is understandable and helpful. As a secondary world, it would just make the rest of the game too easy with all of the free gear and food. If there was a way to disable all of the free goodies (I suspect they're in dispensers somewhere in the ceiling), then we'd have better chances at using the map.
I would like to at least look at the map to see the redstone mechanics. Honestly, I have been planning on making an automated mob arena similar to this construct, but they improved my ideas in every way. :V