I'm not sure that the quilen, Stoneclaw, has a new appearance. I think it's the existing skin. Did Wowhead say it was new?
The bright amber firefly is a new skin on the old firefly model, so that's exciting at least! Hopefully there's a tameable version. I hope it's not locked up in IE.
Wowhead just said that all of the models posted above belong to the battle pets for the next Raiding with Leashes, which will be in MoP raids this time. It is believed that the firefly will drop from a boss in Heart of Fear. The quilen will drop from the four quilen boss in Mogu’shan Vaults.
Ah cool. That seems extremely odd they'd create a new firefly skin for a battle pet in an old dungeon, so maybe it's being used elsewhere too. Either that, or it is an old skin they simply forgot to add to the database until now :/
They just listed the new battle pets on the page, as I *believe* they're all new models for pet collectors. They aren't all new models. (Though some obviously are, like the celestial Quilen)