It looks like the new 5 man Icecrown instance has a blurb on WoW Europe and it's going to be crazy. There are three wings, each wing has its own lockout timer and you'll need to take each one out during an epic quest to advance. Guess who's the endboss? Arthas himself. You get to Jaina and Sylvanas out too. Sounds like fun, right?

Icecrown Citadel will feature a massive five-player dungeon sprawling across three wings of the citadel's foundation. While the Lich King's attention is focused on the Argent Crusade and the Knights of the Ebon Blade ripping through the front gates, players will be tested as they assist Jaina Proudmoore (Alliance) and Sylvanas Windrunner (Horde) in infiltrating the citadel.

Read about Icecrown right here.