Now that MoP, Mists of Pandaria, has arrived to World of Warcraft the Brewfest holiday has just started. There has of course been some upgrades and the achievement for Direbrewfest changed a bit. He’s not a lvl 90. To kill him you need to queue for him in the dungeon finder just like before, you do however need to be minimum level 89 now.
Quote from Crithto:
Word is, Coren Direbrew has been working out with bigger kegs and he will indeed be a level 90 dungeon boss and his loot has been adjusted accordingly. Pace was something we considered, so we pushed the actual event by just over a week from when it normally happens (which you should be able to see on your in-game calendars now) to give players a bit more time to reach level 89, the minimum level required to queue for the encounter. Oh, we also added a couple more surprises but you’ll have to wait and see. 😉