Wowheadnews has some nifty 3D models for the Sand Scarab, Lunar Lantern, Festival Lantern, and... Chromatic Dragon Pet(!?).
Wowhead speculates that Chromatic Dragon Pet will be the guild reward for completing the upcoming 4.3 rogue legendary weapon guild achievement, but so far there's no other information on this companion. There aren't even any spell or item IDs listed for this mysterious pet yet. We'll just have to hang onto the edge of our seats in anticipation until Blizzard decides to give us more previews!