Blizzard now offers patch notes for a version 5.0.4 update for World of Warcraft that's now live on the PTR for their MMORPG. This includes an explanation that "PTR testing is restricted to World of Warcraft game accounts that do not have access to the Mists of Pandaria beta test," and this page has more details on this limitation. The new version includes the typical round of balance changes as well as new features like BattleTag support, AOE looting, a new "Attack on Theramore Isle" world event, and account-wide achievements, pets, and mounts, as explained here.