Although I've been writing about World PvP objectives as implemented by mechanics in place in Azeroth and the Outlands, the Horde players of Eredar (EU) -- roughly 250 of them -- took World PvP to the next level. Organized by Xuron, six raid groups and change gathered forces in front of Orgrimmar last December 22, 2007, and marched on to three capital cities and proceeded to lay the smackdown on Alliance bosses. This movie shows how an awe-inspiring, um, horde of Horde players make their way to Stormwind, Darnassus, and the Exodar and later converge on the Alliance bastion of Ironforge.
According to this post on the EU forums (hope you've brushed up on your... German?), the six raids assaulted three cities simultaneously and killed the Prophet Velen in the Exodar; Tyrande Whisperwind and Arch Druid Fandral Staghelm in Darnassus; and Archbishop Benedictus, as well as Highlord Bolvar Fordragon in Stormwind. After laying waste to the three capital cities (or their leaders, at least), the entire lag-inducing, server-crashing set of raids stampeded to Ironforge and let King Magni Bronzebeard and High Tinker Mekkatorque in on the fun.
Although ironically a PvE endeavor because faction bosses themselves are NPCs, this is thematically and lore-wise the stuff of my PvP dreams. I've always daydreamed about exactly this -- laying siege to all capital cities at once. Kudos to the Horde players of Eredar (EU) for preparing a nice Christmas present for the Alliance. The video is a hefty 245 MB download, but if you have the free time, it's well worth the watch.