Quote Originally Posted by 'Clanked',index.php?page=Thread&postID=159455#post 159455

Is the bear for being the first to do that? or can anyone get it by downing all four?
Anyone can get it by downing all four. When you have the achievement, you get an email from your capital boss (in our case: Thrall) with the mount.
Each boss kill is also a separate achievement, but has no rewards.

For The Horde wowhead article:
http://www.wowhead.com/?achievement=619
For The Alliance wowhead article:
http://www.wowhead.com/?achievement=614

It was so much fun that I'll definitely do it again as soon as possible.
Funny detail: the total event took several hours, but each fight was only 3-5 minutes.