Historian Llore in Stormwind and Historian Ju'pa in Orgrimmar are the questgivers for the anniversary event.
They also sell [pet]Corgi Pup[/pet] for 200 Timewarped Badges!
Yay! More dogs to keep the scheming cats in check!
Edit: great point from Ignis on EU forums http://eu.battle.net/forums/en/wow/topic/17614451666
Rather than using the 200 Time-warped badges from your "main" simply create a new level 1 character or log onto an alt to receive another 200 badges through your mail, then purchase the corgi on that character. BattlePets are Account-wide after all.
I saw many players complain about having to spend their badges on the pup so I thought why not put this info out there for people who are not aware of this.