While you're waiting for Patch 3.3.5 to hit the live servers, you can check out Blizzard's latest preview of the final raid instance in Wrath of the Lich King -- the Ruby Sanctum. European Community Manager Wryxian just dropped by the forums to link the Under Development page for Ruby Sanctum, which contains some new images and (perhaps most importantly, for some) the storyline behind the instance.
"Next to nothing is known about who might be responsible for the assault on the Ruby Sanctum: the black dragonflight is not known for forgiveness or patience, but its numbers in Northrend are surely limited. What force would be powerful or daring enough to assail the stronghold of these ancient wyrms? How could such an enemy sneak by the temple's guardians undetected? Surely an approaching air or ground force would have been caught by Wyrmrest Temple's defenders.
For the moment, the members of the accord and their allies must assume the worst scenario that they can conceive of: that all life within the Ruby Sanctum rests on the precipice of extinction, and only immediate intervention will prevent the red dragonflight from being decimated. They'll find that the truth is far worse."
I think some of us know the truth already! If you're raring to go for a trip into the Ruby Sanctum after reading this, prepare yourself by checking out our guide to Halion, the instance's grand poobah.