Just found this and got my mount with this epic exploit
1.First,finish and turn in all 25 Daily Quests (without the Coren Direbew one)
2.Goto Blackrock Depths like normal,you'll find you still can accept and turn in [Insult Coren Direbrew]
the quest list will now display as Daily 1/25 and 24 left
3.Kill Coren Direbew and loot,if no luck,*you(the one who finished 25 daily) need to leave the instance(open portal by mage,hearthstone),and summon back by warlock* (this is the key point of this exploit: get out the instance and get in again,so it can reset your dailys number in instance)
SO it's better Mage finished 25 quests,he can portal himself back
4.Reaccept the quest,untill all your mates got their mounts
also notice these "dailys" also count in the Achievement [XXXX Daily Quests Complete]
I did about 100 dailys in about 2 hours
"also a good way to get the "Greedy" and "Needy" achievements"
so enjoy this epic exploit brought for you guys!!
*updated, got reported to blizzard and hotfixed on US,TW,EU servers,looks working on CN servers only