Apparently, there is no dragonhawk mount available for players to purchase just yet, but when you take the flight from Quel'Danas island back to the mainland, you fly on the back of a dragonhawk. Also, there is a dragonhawk-riding bombing quest you can run (which Mania says is kind of annoying). Finally, there are new enemy elves who ride dragonhawks, and new silvery-grey ones at that!
If you ask me, it's just a matter of time until Blizzard puts dragonhawks into the game as the latest and greatest flying mount you can get. They'll probably make it an exalted Shattered Sun Offensive reward which is unlocked as that faction's presence on the island grows stronger, or else make it a rare drop from one of the bosses, like the bear mount from Zul'Aman. It would be a true shame indeed to taunt us with all this other dragonhawk riding if we couldn't also get one of our own, after all, and Blizzard isn't that mean... are they?