The attack on the Pale Tree has spurred the world's leaders into action and hardened their resolve. As season 2 continues, the races of Tyria are preparing for war against the Elder Dragon Mordremoth. Echoes of the Past begins November 4!
Prior to that, you can take part in the "Blood and Madness" event that's going on right now. You can find out more on that update and the upcoming Echoes of the Past update by checking out the game update page for Guild Wars 2.