I did some dungeons and quests in the new zones yesterday, and hit level 81 with my priest. I noticed that the new zones are rather crowded around the quest giver NPCs, and that Horde and Alliance often cross paths. That doesn't affect me, as I am playing on a PvE server. But from what I read in various blogs, and hear from friends, this does cause problems on PvP servers: Everybody is concentrated around the same few quest givers, and then the ganking starts.
Now, while not a fan myself, I completely support PvP that has some sort of objective: Be it some battleground, keep warfare, territorial control, that all makes perfect sense to me. But why would a game first force people to congregate around the same few spots to get and hand in quests, and then enable them to slaughter each other there without any purpose?