Patch 5.4.1 was released, but only to implement new and updated pets in the Pet Journal. No new pets have been released yet.
The new additions include Murkalot and Alterac Brew-Pup. The former being the Blizzcon 2013 gift and the latter will come from the Blizzard Pet Store in the future. I expect the Blizzcon pet will be mailed to eligible accounts once we get closer to the convention dates or during the actual convention (November 8 and 9).
Changed pets include the four that were previously only obtainable in Asian regions.