I remember reading recently on a public site that at release there will not be any instanced dungeon content that will be 'raid' based. Meaning that the highest end PvE content will be scaled to be very challenging, but limited to a single group of 6. What they plan to incorporate into the PvE game after release is anyone's guess.
There will, however, be raid content for high end RvR which will definitely incorporate PvE elements into it. Think of standard end game RvR as strategic open field group/raid based PvP, but with keeps to attack and defend, siege weapons to build and employ, keep doors and walls to destroy or repel the attackers from, outlying towers to capture in order to gain a strategic advantage in the area, etc. As one side pushes back the other through a series of keep asssaults, they eventually reach the opponent's capital city. They then lay siege to that. Once they breach the walls of the capital, there are a whole slew of PvP and PvE quests and missions that open up. These will support raids, culminating in taking down the opponent's overall leader. Supposedly the best loot in the game comes from these capital city raids, so this is most likely where the raid PvE oriented player will get to strut their stuff.
And the best thing is that there are 3 different fronts all going on at once (Dwarfs vs. Greenskins, Empire vs. Chaos, Dark Elves vs. High Elves). If you're not doing so well on one front, head for another and see if you can get some momentum going there.
But I'd echo Icthus in that RvR >>> WoW PvP. Having played DAoC, also developed by Mythic, RvR is waaaaay more fun and less of a 'grind' than WoW PvP. It's got a TON more variety, too.
And yes, this information is all publicly available. I've done veeeery little PvP in beta so far, and nothing that could properly be called RvR.
