With patch 3.3 released to the servers, the froswing Halls will be availbale for play, and thus the entire Icecrown citadel will be ulocked, and with it the lich king encounter itself.
For information about specific boss strategies visit: Dreamwalker Tactics, Sindragosa Tactics, Lich King Tactics
This also means, the beginning of a new arena season!
To those of you who can not wait to defeat arthas himself, below is the cinematic of how this encounter end once you have defeated the lich king.