Here we see Noah Ringer as Aang in an Air Nomad Temple striking a badass pose. If you look closely, you can see the arrow on his forehead.
The only other picture released was of Slumdog Millionaire star Dev Patel as the Fire Nations Prince Zuko. The shot released doesn't show the side of his face that would be scarred, but hopefully it is for continuity sake as it is very important in the series.
An interesting note, both of the stars pictured have a background in martial arts, though not the styles that their "bending" forms are based off of.
The teaser trailer will be played with Transformers: Revenge of the Fallen which opens later this summer and The Last Airbender opens July 2nd 2010.