Hey!
Yupp they used LightWave and the LWO- format directly for Doom3.
The format is a bit oldfashioned, but not that hard to use. We used it successfully in our own 3d- engine back in the days, when we were still looking into doing game- development for profit.
Right now we are more into doing plugins for LightWave (see my avatar).
Wintermute makes me think about trying some game- dev again, once I have the time and the money. Thats why I am browsing these forums.
LightWave also has a .X- exporter. Never really tried it myself since I did not know where I could use that format anyway. Maybe I will give it a shot with Wintermute.
The real beauty about LightWaves format is though, that you have vertexmaps stored in the Object- file. Thats vertexcoloring, vertexweights (for bones and for surfacing as well as SubDivisionSurface- weighting and for morphs. The Format also allows to store a basic skeleton into the object- file with something called Skelegons. Plenty of cool options for game- development I would say
CU
Skipjack