"Every two years, the Spirits of Competition grow especially fervent, and draw close to the mortal realm. During such times, members of both the Alliance and Horde can honor the spirits and earn Competitor's Tabards by seeking to defeat one another in the battlegrounds. For victory in competition, they can also earn the spirits' favor in the form of a prized gold medal - and the special pet it summons."
[Competitor's Tabard] - Mailed to all participants in any battleground, both winning and losing. You MUST have stayed for the full duration of the battleground.
[Gold Medallion] - containing the 'Spirit of Competition' Small Pet (small red and yellow Asian-style dragon). Every time you win any battleground, you have a chance this pet is mailed to you. (It was stated to be a 50% chance each time you win, but this appears to be incorrect. What fits the observed win comments was that it was automatically 'rolled for' among the winning team characters. Also stated "The battleground you play doesn't matter", it appears it did matter, smaller battle grounds (Warsong Gulch) gave better odds of obtaining this pet.)
The fact that this event will happen every two years suggests that it will occur during the years of both the Summer and Winter Olympics. The 2010 Winter Olympics began February 12, 2010 in Vancouver, British Columbia, Canada, lasting until February 28, 2010; however, no corresponding Spirit of Competition event appeared in-game. Upon questioning, Blizzard employee Malkorix revealed that it will only happen in the summer, regardless of when the Olympics occurs. Despite the original statement, the event has yet to recur.
The fact that the inaugural event's small pet reward was themed to the Olympics host country (China) suggests that future instances of this event will offer small pets themed for their host country, and hence will not be repeated. However the fact that the small pet and the event share a name ('Spirit of Competition') also points to the possibility that the same pet may return. The tabard, which is themed to the real world event the game event corresponds to, is likely to remain as an award.