Blizzard has always been cyclical with its content inside of World of Warcraft, especially when it comes to its PTR builds. When a new expansion is announced or a new patch is on the horizon, Blizzard updates the PTR with the content and allows players to test out the builds.
It's rare that new features aren't paired with an expansion or something completely separate from the game. So it's a bit of a surprise that the PTR is getting something new so soon after an expansion release and before the 10.1 content drop.
World of Warcraft's Trading Post Feature
The Trading Post is a new way for players to log on, grind out quests and earn currency for cosmetic transmogs, pets, and mounts. These three things are some of the best content outside of actual gameplay and rewards. Blizzard always has to balance content with power levels, meaning they don't want to tie massive grinds with power levels, forcing players to play dozens of hours a week to stay relevant. Instead, they reward optional content for players who want to earn a new mount or pet.
So far, the system is pretty straightforward:
"A new set of traders will be moving their wares into the capital cities of Stormwind and Orgrimmar—T&W (Tawny and Wilder) and Zen’shiri Trading Posts. You’ll find T&W just outside of the Mage District in Stormwind and the Zen’shiri Trading Post next to Grommash Hold in Orgrimmar. Our trader friends have pulled out all the stops and have set up their shop so you can view the new items of the month prominently on display right at their shop. They’ll have transmogs on mannequins, pets at their feet, and mounts secured in their stable. Speak to the traders to see this month’s wares."
Completing weekly and monthly quests and tasks will reward players with that new currency and they can choose to buy what they want. A new Traveler's Log will keep them updated on monthly tasks and show how far away they are from completing those quests. The good news for more hardcore players is that tasks can be tied to dungeons and battlegrounds allowing them to play their favorite content and still contribute to the Trading Post.
The post states it will arrive on the PTR soon, so keep your eyes out if you want to test out the new feature for Blizzard.