It's just a game that ALL hardware vendors take part in, not just NVIDIA. From Ars Technica:

3DMark03 benchmarking shenanigans update
I missed it on Friday, but ATI fessed up to "optimizations" on game test 4 of 3DMark03. Beyond3D carried an explanation from ATI's director of smooth talking.

"The 1.9% performance gain comes from optimization of the two DX9 shaders (water and sky) in Game Test 4. We render the scene exactly as intended by Futuremark, in full-precision floating point. Our shaders are mathematically and functionally identical to Futuremark's and there are no visual artifacts; we simply shuffle instructions to take advantage of our architecture. These are exactly the sort of optimizations that work in games to improve frame rates without reducing image quality and as such, are a realistic approach to a benchmark intended to measure in-game performance"

ATI has decided to take the optimizations out in the next Catalyst driver release. One company's cheat is another's optimization and there is a lot of gray area in between. In a /. discussion on the incident, The Carmack weighed in with his opinion.

Rewriting shaders behind an application's back in a way that changes the output under non-controlled circumstances is absolutely, positively wrong and indefensible.

Rewriting a shader so that it does exactly the same thing, but in a more efficient way, is generally acceptable compiler optimization, but there is a range of defensibility from completely generic instruction scheduling that helps almost everyone, to exact shader comparisons that only help one specific application. Full shader comparisons are morally grungy, but not deeply evil.

From previous run-ins with Futuremark over 3DMark03, it appears Nvidia set out to discredit the benchmark even if it caused them PR nightmares. I am surprised that ATI tried to let an "optimization" slip through even after their previous Quack3 debacle. Nvidia almost seemed to justify their actions with the claim they weren't involved in the Futuremark BETA program (left out of disgust?). ATI had no excuse for using a questionable optimization. Since they were a BETA partner, they easily could have gotten feedback from Futuremark directly.