Well the new world event quest activation has something to with 3 things

1) Selling SOJs to vendors (looks like Blizzard is still trying to get rid of the duped soj's)

2) A super "Diablo Clone" that spawns somewhere in the realms after you activate, its suppose to be lvl 110, a message saying "Diablo Walks the Earth" will show when he is spawned

3) This super "Diablo Clone" when slain, has 20% in norm, 80% in nm, and 100% in hell of dropping annihilus, the unique charm that gives extra XP %