Gold Mini Jouster

One of the pet rewards you can choose upon completion of Egg Wave. Looks like a gold/brownish buzzard that has a gold rag doll "jouster" riding on its back, holding a jousting lance. When summoned, it appears in a beam of light (a la Joust) and with the same horn sound effect that occurs when you cap a WSG flag. (edit: sound effect has been removed)

Looks identical to the Blue Mini Jouster (despite current difference between the UI icons) except that one has blue coloring instead of gold.

Additional note: I summoned my Blue Mini Jouster next to another player who had the Gold Mini Jouster, and we both stood there for awhile to see if there would be any hot pet fight action. There was not. :(

(edit: The info below is out-of-date since Blizzard seems to have removed this functionality before it left Cataclysm's beta, but I'll keep it here for archival purposes)
Update! So it seems that this pet does have some fight in it after all. I still haven't seen one fight another Mini Jouster of either color, but I have seen it attack actual mobs! I haven't yet been able to narrow down if there's any particular pattern to it or not. However, every once in awhile, the pet will start attacking a mob I'm fighting, and, when multiple mobs are present and engaged (e.g., ambush quests), I've even seen the pet attack a mob that I was not targeting but was attacking me.

The pet itself is level 80 with around 31k hp. It can be hit by mobs and "die." I've seen it hit lvl 84-85 mobs for around 770 dmg per hit (with glancing blows more common at around 550-660 dmg). Despite these numbers, it even seems to draw aggro on occasion, so it almost seems as if there's a Growl going on at times as well.

One note of caution is to be careful when you take off on your flying mount and leave this fella to trail along. At the moment, it seems to hover closer to the ground (rather than following right next to you on your mount), and I have seen it aggro ground mobs while I've been in flight. This puts you in combat as well. Will update further if I see anything else fancy with this.

I have the blue one, but I assume these guys function the same. I have yet to see any pulling or even attacking on its part, but it does not skim the ground when you're on a flying mount. It flies along with you. :3

Edit:
As of 4.2, you can now go back to the quest-giver to do a daily called Vigilance on Wings. Do it ten times and get an achievement as well as a Chirping Box in the mail containing whichever jouster pet you didn't choose the first time around.

Unique Features
The Gold Mini Jouster is not a unique companion pet because it shares the same model with the Blue Mini Jouster. This pet has pretty generic animations and shares the animations that in-game condors have. When this pet is summoned, the owner will /cheer and a flash of gold light will appear.

How to get it
This pet is a reward from the quest Egg Wave in Mount Hyjal. You have the option between picking this pet, or the Blue Mini Jouster. Be confident with the color of mini jouster you want to have as your companion as once you complete the quest and accept your reward there is no way to change your choice.

Source: Warcraft Vanity