Caverns of Time - Wowpedia - Your wiki guide to the World of Warcraft
Today I discovered you can find Kel'Thuzad in "The Escape from Durnholde" Caverns of Time dungeon. He is in Southshore talking to Helcular about Necromancy and breaking away from the Kirin Tor. :
Caverns of Time Zone - Dungeon Guide
Keepers of Time Reputation Guide - Wowhead
Caverns of Time - Wowpedia - Your wiki guide to the World of Warcraft