Arena has released a new Guild Wars 2 dev diary. In it, developers talk about World versus World and the basic fundamentals of Player versus Player combat, on such a massive scale. Based on the video, siege warfare seems to be the central focus of WvW.
Controlling supply lines, like you would in a Real Time Strategy game, allows your team to build up enough resources, to assemble massive siege engines. Or, alternatively, reinforce and repair defensive structures.
In fact, speaking of an RTS game, GW2’s WvW combat feels just like playing an RTS. Only, you’re playing as an individual unit. Personally, I think this is genius, as I’ve always wanted to experience war on such a massive scale, with such an individual perspective. Even many of the strategies seem to be the same. You and a few friends can harass the enemy teams supply lines, disrupting their economy.
Much like harassing someones economy with mobile, expendable units in an RTS game. Or, alternatively, you and your guild can formulate a complex strategy and set up a full on assault to break a keep. Much like performing a coup de grace on your opponent in StarCraft, with your perfectly assembled mix of complimentary units that specifically counter what your opponent has.