Back in October, Blizzard teased the Swift Windsteed mount
on their Facebook page. Further information on the mount trickled out via datamining patch 5.1
-- and as of this morning, it's available for purchase on the Blizzard Store
for $25, though there is only one color available as opposed to the many that were datamined.
Swift Windsteed – Exclusive Mount Now Available
Take the reins of one of Pandaria's most majestic and rare beasts, the Swift Windsteed, and it is said that good fortune will follow. Dart across the heavens on a silver cloud as fast as your riding skill allows. Once purchased from the Blizzard Store, the mount will be available to all present and future characters for a single Battle.net® account.