There was concern that South Korea's rating board was throwing a monkey wrench in Diablo III's certification. If the game went unrated, then Blizzard's planned worldwide release would go right out the window.
The Korean Game Rating Board finally rated the game, giving it an 18-and-up rating. What was holding up the game's rating was the Diablo III's "auction house" feature.
Now that's rated, all systems go for a worldwide release!