While dungeons should remain integral to our evolving storylines, and great places to collect gear in cooperative environments, we need to make sure each player’s questing progress remains relevant as dungeon quests are completed. In many cases we’re seeing players enter dungeons to complete quests, only to come out ahead of the leveling curve for the zones they’re in.
This change should allow players the opportunity to reap the benefits of running dungeons, while not outpacing the leveling flow from levels 1-60. At this time there are no plans for making any adjustments to dungeon quest experience for Outland, Northrend, and level 80+ Cataclysm dungeons.
You can find a list of all of the latest hotfixes here: http://us.battle.net/wow/en/blog/1232869