**UPDATE - July 2, 2009: Further info about differences between Na'vi and Avatars! Jim here again. Here is what my source has to say: "There is major difference between the Na’vi and the avatars. It was visible in the footage shown at Amsterdam, but the viewers were so stunned they didn’t notice. The Na’vi have four fingers and toes; the avatars have five. In addition to the eyes, the avatar’s nose is also slightly smaller than the Na’vi’s."
Pay attention guys! :-) That includes me!
**ANOTHER SAME DAY UPDATE: Exclusive insider info on the Na'vi image in the poster - this is from a trusted source: "Since one of the viewers of the Amsterdam presentation already mentioned it, the avatars do look somewhat like their human counterparts. This means the Na’vi look less human. Larger eyes for one. (Jim: Actually heard Neytiri has a striking resemblance to Zoe Saldana).
Unfortunately, geometric distortion was introduced when people photoshopped the banner picture, which was slightly oblique, to generate a full-frontal view. This made the facial features look smaller in relation to the size of the head, as well as distorting the nose.
The glowing spots are on the face, not an overlay of a star map. Whether they are naturally-occurring markings, tattoos made with bioluminescent bacteria, emanations of mysterious psychic powers, or simply applied dots of glowing makeup must be left to your readers’ imaginations at present."
Interesting!! Comicon is the place to be...
UPDATE: Now with the original, higher resolution pics from the official Comic-Con Twitter feed. Click for the big versions.
Here's an enhanced version of the poster and a full-face manip, courtesy of "Ludovic":