Having just seen the new version this past week, I can elaborate a little. Warplots are basically a giant base/fortress that utilizes the same tech we have for housing. Normally it floats in the sky (Instanced, like your house). You and your "Warparty" (which can be a totally different group of people than your guild) can go in and edit which defenses it has; this can be anything from preset plugs to freeformly placed traps like mines and controllable turrets.
Once setup is done you can queue for a match. You and another team's warplot will be brought to a static map and the fight begins. I can't go into details about how the fights play out yet, but there are a few win conditions and a lot of variation on how to attack the other team. You could fight on your own, for example, or you could camp out in your base and summon waves of robots, helicopters, and chompacabras.
Actual details will be shared early next year, but it's definitely THE ultimate endgame for PvP. (In addition to arenas and battlegrounds of course.)