So far the UHMM does the following:
Exports JMS files from objects in a scene (with their in-scene coordinates)
Exports JMS of terrain + sky (works almost perfectly, just some ground texture problems)
So, I made a map with a large mountain in the middle (a REALLY big one)
I'll get some pics from my re-import in 3ds max.

Everything except for the skybox was made in the UHMM using the TerrainBuilder. The skybox was exported as an E3D (read ye old UHMM topics for more info) and then stuck into the UHMM.
It was then implemented into the exporter.