Blizzard Producer J. Allan Brack also talked in the latest issue of PC Gamer about Wrath of the Lich King, and while he doesn't drop any major bombs, he does speak pretty candidly about what Blizzard is doing right and wrong with content, and what they hope to achieve from World PvP in the future.
Perhaps most surprisingly, he gives away just how closely Blizzard is watching their competitors in the MMO world to see what's worked and what hasn't -- on the issue of updating the graphical engine and just general influences, Brack has no compunctions about citing EverQuest as a huge influence on World of Warcraft, even going so far as to call it "the big foundation" of the game Blizzard made. He also notes that Blizzard pays a lot of attention to their own game as well -- they track how fast players are going through content, and how players do it. He specifically says that Lake Wintergrasp PvP will work like the Spirit Towers in Auchindouin, in that the battle will go down at a certain time, so everyone knows when to get to work and fight there. Battlegrounds and arenas aren't being neglected, either -- there'll likely be "at least" one of each added to the game with the expansion.
Finally, he also agrees that "level separation" (the difference between the characters you've got and your friends who just joined up at level 1) is a problem that Blizzard is keeping an eye on, and while he doesn't mention any solutions yet, he says they'll change it if they feel they have to. Sounds like Brack and his team are well on their way to hammering out the expansion.