As most of you probably know, Zul'Aman is the troll-related instance sitting idle in the Ghostlands of Azeroth. MMO-Champion (may have come from another, source, don't know) has put up some loading screens, and it seems that they have Black Temple, etc. but also Zul'Aman's loading screen.
We never heard anything from Blizzard about this instance so, if it's patched in, it probably won't be before 2.2. But loading screen in itself is menaningless, there are many arts, spells, textures and such in wow client for future content. There are emerald dreams files in the wow client since closed beta US and 2 years later, it's still not used anywhere.