This is the current change pallet for Forge Island to the best of my knowledge, It may just be beta so it could all change but currently:
Scenery is the only one changed:
-Natural has a few new rocks as well as 3 new placeable trees
-Buildings for some reason has 2 rocks, one pillar and one wall.
-Forge Island, the pallet is the same as ravine, except it has a new block called green screen
The map itself is incredibly tall, almost a perfect cube... and thats all thats new... I think
ALSO DOWNLOAD IT NOW OFF THE XBL MARKETPLACE!