A week after patch 4.0.3a went live, Blizzard has decided to make a fairly substantial change through a hotfix. Zarhym hit the forums to make everyone aware of a reduction in quest experience for all dungeons in the 1-60 range.
The main reason for the reduction, according to Blizzard, is to ensure the level progression remains intact even if you take breaks from the overland zones to run an instance. In many cases -- including my own personal experience -- dungeons would put the player far ahead of the leveling curve when they were finished. This was primarily caused by the large amounts of experience awarded by the dungeon quests.
With the ease of completing them, I can certainly understand the reduction. The Stockade offered three quests that were all very easily completed in a group using the Dungeon Finder -- even when I had to tank most of it as an Enhancement Shaman due to our tank... well, not being a very good player.
In a way I'm kind of sad that dungeons aren't quite as lucrative anymore, but at the same time I'm okay with the fact that I won't have to skip entire zones now due to gaining multiple levels on a 20-30 minute dungeon run.
We are applying a hotfix today to all level 1-60 dungeon quests for Kalimdor and Eastern Kingdoms dungeons which will significantly reduce the amount of experience they award.
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