It seems that the wallpaper (image on center) Blizzard gave us some time ago was cropped,
this can be seen from the creature "parts" on the wallpaper borders
I got my hands on images taken from Blizzard HQ (Headquarters) and I realized that
some of them matched with the wallpaper! (Right and left images)
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Proof: look inside the red circle!
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UPDATE: Video!
[ame="http://www.youtube.com/watch?v=efKT9Av6NxM"]YouTube- [WoW Cataclysm| Leaked Concept Art - Creatures & Landscapes![/ame]