At first tought I think that it would be that GbaTemp is making some sort of Nds emulation since Mario's kart seems so deformed... but now I can't have ideas on what that photo means
well whatever this means , is that GBA temp seem to have a copy of mario kart ds, as it has been confirmed that you can use the touch screen to create custom decals for your kart. :-)
I think Gbatemp has played to the game, and has taken some shot
it doesn't prove that they have the game, you can play it in a game expo for example ^^ ( who said "micromania game show" in Paris this WE in the back ?
As far as i know there isn't a polygon model maker for the DS version, only for the revolution version. I think it's from the Mario Kart DS carpaint editor.