Great news, and a big thanks to the hard working developers! I want to try out the Lua scripting at some point.
Besides the original Morrowind, I've also read that both of the major mods, Morrowind Rebirth and Arktwend (which has a special OpenMW port available on NexusMods), can be played using OpenMW.
Considering that not many people use BSD or the others, I would guess that most of the "unknowns" are actually Linux users. That means we're probably already at over 6%. :-)