Patch 4.2 added a fair amount of models to the game files, see the newest ones below!
Both Horde and Alliance got brand new PvP mounts, they seem to be a reward from the existing rated battlegrounds achievements. It's not very clear which achievement is required, Blizzard is probably still playing around with those:
- Veteran of the Horde Win 100 rated battlegrounds.
- Warbringer of the Horde Win 300 rated battlegrounds.
- Veteran of the Alliance Win 100 rated battlegrounds.
- Warbound Veteran of the Alliance Win 300 rated battlegrounds.
Tarecgosa and Tarecgosa Whelp
Tarecgosa, the blue drake from the legendary staff questline got her own model. There's also a model named "TarecgosaWhelp" and I really want to believe that it is the Dragonwrath Whelpling rewarded by Dragonwrath, Tarecgosa's Rest - Guild Edition. There is no indication in the game files yet that it is indeed the reward, I will try to confirm that as soon as possible.
Malorne is also in the game files and got a pretty nice model. For more information check Malorne on Wowpedia
Fandral Staghelm + Fire Scorpion
Fandral's model and his Fire Scorpion forms have been added.
Lord Anthrycist - Lava Form
It looks like Lord Anthrycist's fight will have two phases, he's much more fiery in one of those.
Two sets of Lava Spiders models have been added in this patch and they look awesome.
Winged Lion Pet
Yes. Seriously. So much cuteness.
Fire Elemental - Kar
A new Fire Elemental "Kar" model appeared in this patch, not sure if it's just an updated trash mob model or a boss.
Ragnaros has been slightly revamped and looks a lot less stupid than in the Patch 4.1 game files.