Blizzard originally proposed three new battlegrounds at BlizzCon, but has trimmed it down to two for Mists of Pandaria's release.
They are also trying to revisit world PvP to make the world more alive. The more locations players fight on and win for their faction, the more conquest points their weekly cap will allow.
Temple of Mogu Located in the middle of the Vale of Eternal Blossoms, players vie to pick up and control an ancient artifact. This artifact gives the player a damage buff but also increases damage taken--the goal is to have the artifact constantly changing hands. Another twist is that different parts of the map award varying amounts of resources--holding onto the artifact in a risky area of the terrain will yield more resources per minute. This is intended to be a fast-paced BG in a new style from previous ones.
Silver Shard Mine Underground area with mineral-rich resources that travel in mine cars. These mine cars are capture points--think of EotS, but moving. The Alliance and Horde want to capture these mine cars before they get to the depot, and at various points on the rails, there are splits where the mine cars can go either way. Depending on who controls channel points, the cart can travel different ways.
World PvP Conquest point cap will increase as players win world objectives. For example, personally conquering Southshore and Tarren Mill back in the day would have been great for this dynamic.