The head at Bungie, Harold Ryan recently confirmed that Halo: Reach might be compatible with Microsoft’s Project Natal.
This is not a direct confirmation that Halo Reach WILL USE the Natal camera. The way i see it, it seems quite possible but i doubt that it would be entirely controller free. They might use the camera for specific levels in the game. That would be quite an experience when playing video games, especially a game like Halo.