According to Blizzcast 16, it's awarded at the end of the Firelands daily questing zone, which has approximately 60 total daily quests. Unsure what the exact requirements might be.
EDIT: larger link here: http://us.media4.battle.net/cms/gall...4015909454.jpg
EDIT: More random info about the Firelands dailies; they will progress on an individual level that will supposedly include a phasing system that still allows you to do daily quests with people who aren't in the same phase somehow. You unlock daily quest clusters in randomized stages as you do different dailies, so basically you have to complete certain dailies in order to unlock other dailies. Vendors unlock as the main hub, a druid tree being grown in the Firelands, expands and grows larger while you progress through the daily zone.
P.S. the guy who hosts Blizzcast makes me want to rip out my soul through my own eyeballs. something about his facial expressions