From WoWWiki
Of Gnomeregan is a title awarded to Alliance players upon completing the achievement 
Exalted Champion of Gnomeregan, which requires the player attain exalted status with Gnomeregan Exiles and earn the right to represent Gnomeregan in the Argent Tournament.
Gnome characters can obtain this title by completing 
[80] The Valiant's Challenge (Alliance). Characters of other Alliance races must complete their version of The Valiant's Challenge, then complete [80] A Valiant of Gnomeregan.
Patch Changes
[80] The Valiant's Challenge (Alliance). Characters of other Alliance races must complete their version of The Valiant's Challenge, then complete 
