From what I understand, it's a sort of viewer (there already is one for rF2), but one where you can edit the materials and stuff and see the result in realtime. Contrary to 3DSimEd, it shows the same thing you'll see ingame.
If you have a 3D model, mapped and everything, you won't need 3D Studio Max anymore to get that ingame.
Some people think it's the one thing needed for modding in rF2, but unless it's really powerful, I'm not expecting miracles in terms of content produced.
_________________
http://newarchive.simjunkies.org/discussion/9582/asj-f1-1982-race-4