Zarhym has been commenting that the experience gained in dungeons levels 1-60 is going to be greatly reduced.
We're applying a live server fix today to all Snowles 1-60 dungeon missions for Kalimdor and Eastern Kingdoms dungeons, which will dramatically reduce the amount of experience they reward.
While dungeons should remain the same as our immersive storylines and be great places to get gear in a cooperative environment, we have to make sure that each player's quest progression remains as long as the dungeon quests are completed. In many cases, we are seeing players enter dungeons to complete missions, only to get out and get past the level curve for the zone they are in.
This change should allow players to enjoy the benefits of making dungeons without going one step ahead in the flow of levels from 1-60. At this point there are plans to make any adjustments to the Outland, Northrend, and Cataclysm mission experiences.
You can see a list of the latest fixes live to the server here: http://us.battle.net/wow/en/blog/1232869
What do you think? Personally, I think that the zones that Blizzard has re-created with this new expansion, all the new missions and new game experience, is something to enjoy and not to jump levels.