Valnoth announced today that with the return of King Wrynn in Wrath of the Lich King, Blizzard will be removing the attunement necessary for Onyxia. In vanilla WoW, Ony was an achievement and many peoples first introduction to raiding in Warcraft. In Burning Crusade it was often ran as a quick way to make a buck or get a nice helmet for an alt.
Ony was one of the last, great old school attunements required in the game. With it gone, only Black Wing Lair and Molten Core remain as attunement required raids. This is a sad day for those of us that enjoyed the quest chain. A friend of mine and I were going to run this through on his Shaman and my up-and-coming Mage. Apparently we'll have to actually kick ourselves into gear and do it soon.
There is no indication if this change will come with WotLK or with patch 3.0.2. However the King returns in 3.0.2, so I would have to assume the attunement will be lifted then. It should be noted however, that Valnoth did say they would attempt to return the chain some day in the future. But we all know how that can go...
Thanks to Jarred for the tip!