The blogger who's titled himself "Lume the Mad" (ahem) has an interesting take on the lore surrounding World of Warcraft's lore for the Burning Crusade as a whole, and the patch 2.4 content drop in specific. According to Lume, Blizzard needs to make a better effort in the future towards keeping everything in-game. As it stands, the final encounter in the Sunwell dungeon is nigh-incomprehensible if you're only using in-game references. The final interplay between Kalecgos, Aveena, and Kil'jaeden is perfectly understandable if you follow WoW Insider's excellent "Know Your Lore" series, but otherwise you'd have to read a few graphic novels to get the full effect of the dungeon's climax.
Lume compares this storytelling to the way that the television show Lost approaches lore. There are pieces of story spread around various types of media - videogames, books, websites, podcasts - all of which expand on the Lost world. The key is that none of these 'extra' components are integral to the television show's story. They enhance, rather than prop up, elements of the show's plot. In WoW, that's not the case - you need to read these manga, effectively, to really get what's going on. As we look forward to seeing a lot of Arthas in Wrath of the Lich King, let's hope the company keeps in mind what players have and haven't seen to date in-game.