Dragonhawk mounts became available with Patch 3.0.8 which added the achievement, even though the dragonhawk models were already ridable as early as Patch 2.0.1 and flight masters in Quel'Thalas were given dragonhawk taxis with Patch 2.4. Three epic quality mounts are currently available to players. Of these, one is exclusively attainable by Alliance players and two are for Horde aligned players.
Mountain o' Mounts
The reward for earning this achievement is a dragonhawk mount. A blue one for the Alliance and a red one for the Horde.
The reward for earning this achievement (added in Patch 5.3) is an armored dragonhawk mount, a blue dragonhawk for the Alliance and a red dragonhawk for the Horde.
Trading card game
This mount is obtained by redeeming the associated Trading card from the "Twilight of the Dragons" expansion.