Exterminium earned the achievement
on February 3rd, 2010 at 5:14 am
That was during Wrath of the Lich King, when the achievement was harder.
* Shen'dralar reputation was removed as a requirement in patch 4.0.3 (Nov 3010).
Progress is pulled in real-time from the battle.net API. The value shown here is either the current reputation or the one recorded by the achievement - whichever is highest.