The Nikon Photo Contest International has been held by Nikon since 1969. The application period is from September 1st till November 30th 2008. More info on how to apply can be found here.
Grand Prize:
Nikon Digital SLR Camera D3
AF-S NIKKOR 14-24mm F2.8G ED
AF-S NIKKOR 24-70mm F2.8G ED
Good luck!