Modk of Juggernaut has obtained the world's first Shadowmourne! It's the final legendary weapon in the Wrath of the Lich King expansion (at least, that we know of) before Cataclysm is due out. The quest line to earn the weapon is both costly and long. So a big congrats to Modk! I suspect we'll gradually be seeing more and more of these. Who knows how many we'll have by the time the new expansion is released?
If you're curious to see the proc of the weapon in action, check out the video on MMO Champion.