It hasn't shown up on the Beta servers yet, but it's probably still one of the most eagerly anticipated instances of Wrath of the Lich King, especially for us old timers. I'm talking, of course, about The Culling of Stratholme in the Caverns of Time.
The nice thing about the Caverns of Time is that you can do stuff like this, sending people back to visit pivotal places, people, and things in the past without creating a whole new game. Despite the stumble in Mount Hyjal, when we appeared to go as tourists instead of agents of the Bronze Dragonflight to combat the Infinite Dragonflight, the Caverns of Time has been solid and well-liked, with 5-man instances that allow you to experience some important and intriguing lore and give you a definite story to follow in the instance, one that can be done in well under an hour.
Certainly, this model has lead to a lot of fans, and a lot of people hoping we'll see many more CoT dungeons to come. There's even rumors (or wishful thinking) that we'll get another Caverns of Time raid for Wrath, possibly The War of the Shifting Sands.
Whether it's true or not, I can't say, but the caverns definitely have room to expand. As the custodians themselves explain, passageways to new times could open up without warning, sending us off on new adventures. What times, places, and people would you like to visit via the caverns?