In PlanetSide 2, players will be fighting for territorial superiority. Territories and regions will be fought over as part of an overall metagame. Regions provide the faction with resources when controlled.
The sanctuary continents from the original Planetside will not return, cited as a cause for slowing down the pace of game play, instead all empires will have uncapturable facilities on some continents.
It seems territory is won by capturing the local facility or, possibly, other structures. Facilities, and therefore territories, can be captured even in isolation. This is in contrast to the original game, where you could only capture facilities adjacent to ones you already own.
However, capturing a territory in this way suffers a penalty - for example, it may take significantly longer to take down.
Territorial control will be persistent. The rhetoric suggests that this will create a dynamic and ever-evolving battlefront.
Structures such as large facilities and towers will return. Smedly pointed out that the tower in the first trailer video had "landing struts" which suggests that towers can be dropped into territory where they previously didn't exist. Matt also comments that resources in the future may allow outfits to construct towers and facilities, suggesting that outfits will be able construct towers and drop them into position on the battlefield - presumably to aid in defence. 
Upon release, Planetside 2 will have three continents, each supporting up to 2000 players. The number of continents may go up as the game progresses, and the developers add to it. Indar, the only revealed continent is 64 square kilometers.