Obviously it's easier for a developer to not have to... you know... develop stuff but that's their job. To accept a method from nVidia that locks out ATi is disgusting. We want open standards and free competition, not shady deals that punish gamers not owning the "right" card. What next, games or levels that only work on nVidia cards? DirectX sub-standards that are incompatible between vendors?
I'm all for manufacturers working with developers to improve the performance of games but not at the expense of the competition. Adding PhysX is great, but disabling it with ATi cards present is not and not if they're going to deliberately nerf CPU performance. 3D Vision is great, but again I'd rather see standards implemented through universal specifications like DirectX. Having a "solution" that works only with nVidia hardware is no "solution" at all. You don't have to worry about which brand of processor you buy, only its performance - the same should apply to graphics cards. It should be about performance, not manipulation.
The reality is that nVidia isn't as competitive on performance as it used to be and is resorting to dirty tricks to maintain or increase marketshare.