The current reward is a Proto Drake. That is a WoTLK mount. Will blizz put a new reward that is a cataclysm mount?
I read in the patch notes... for 4.0.3a
"Achievements
* The Gladiator reward mounts now award Master Riding.
* What A Long, Strange Trip It's Been now awards Master Riding."
So I'm wondering myself if that means fully, you no longer are rewarded a mount, but just the Master Riding... Seems kind of silly if you buy the flying, only to get it as a reward. Because I have yet to finish the Achievement.