Greg "Ghostcrawler" Street has joined Riot Games as lead game designer. Previously Greg was lead systems designer on World of Warcraft where and his involvements with the game were huge.
He led half of the design team, and oversaw the development of various aspects of the game from class, items, professions, combat, PvP, UI, and major feature designs. Greg shipped three expansions in his time with Blizzard, and contributed to two others.
Greg started with Riot Games in December, and it's not a bad move at all. World of Warcraft reigned king for the longest time, and it's pretty safe to say that League of Legends is the new ruler in the PC scene.