Last week, Blizzard released a new machinima movie called Lament of the Highbourne, featuring Sylvana's performance of the old Quel'dorei song and a retelling of what went down between her and Arthas Menethil, now known as the Lich King. WoW Insider, being the extreme lore geeks that we are, has put together a video analysis of the movie that Blizzard released, featuring an almost frame-by-frame commentary about Sylvanas' story. You can see the finished product above-- prepare to be lore-geeked out.
Two things that didn't make it into the commentary above in time: reader Lift sent us a bit of insight about Arthas riding an Undead mount-- does that mean, he asks, that Death Knights will get their own Warlock/Paladin-esque mount? And one more thing we noticed-- the spectre behind Arthas as he resurrects Sylvanas may well be the Lich King himself. By all means: discuss.