We are just on the rumor / speculation phase still, anyway
RPGDot seems pretty confident that the add-on is now in development and it is rumored to be available this November.
Since we got confirmation from three reliable sources (that's our standard for not counting something as a rumor): Bethesda Softworks will announce a Morrowind expansion called "Tribunal", to be released in November, this week. The expansion will include:
- Mournhold, the ancient capital city of Morrowind.
- clockwork city of Sotha Sil
- epic sized dungeons
- goblins, liches, and other creatures
We will, of course, keep you updated about this expansion whenever we can tell you more.