The End Time will be the first of the three new 5-man dungeons coming in patch 4.3. Blizzard's previous announcement laid out the general story for the dungeon, as well as some excerpts from the Dungeon Journal.
The other new dungeons are the Hour of Twilight and the Well of Eternity. The new raid in patch 4.3, where you go up against Deathwing, is called the Dragon Soul.
Brace yourselves for what could be some of most exciting updates to the game recently with patch 4.3. Look at what's ahead: new item storage options, cross-realm raiding, cosmetic armor skinning and your chance to battle the mighty Deathwing -- from astride his back!