Today the official “Under Developement” page was updated giving some insight on the next major content patch. Some of the upcoming new additions include:

• The Argent Tournament Expands: With the help of Azeroth’s heroes, the Argent Crusade will finish the Argent Coliseum just in time to call for all brave citizens to prepare for battle with the Lich King. New dailies, rewards, and more will be available at the Argent Tournament grounds to lure adventurers into the coliseum.
• Crusaders’ Coliseum: In order to prepare for a siege on Icecrown Citadel, players will be called by the Argent Crusade to test their mettle in the Coliseum. 5-player, 10-player, and 25-player challenges await inside.
• New Battleground: Isle of Conquest, a new large-scale siege Battleground, will be open. The Horde and Alliance will battle head-to-head for control of strategic resources to lay siege to the keeps of their opponents.
• New Arena Season: Season 7 will officially start, paving the way for all-new items and challenges.

No word on when it will hit the PTR.