How so...?
The opening sentence should be a clue:
Nvidia has long promoted its PhysX game physics middleware as an example of a computing problem that benefits greatly from GPU acceleration, and a number of games over the past couple of years have featured PhysX with GPU acceleration
If you use nVidia graphics then the PhysX compute on CPU is a moot point.
On the other hand, AMD graphics owners basically flood forums telling all-and-sundry how PhysX/Physics is a complete waste of time, a fact seemingly borne out by how little AMD invests in open source Physics engines like Havok and Bullet (at least up til this point in time), that are optimized for CPU computation- that is to say, past the
usual PR related notices.
So we have a situation where either AMD follow through "Gaming Evolved" (and better game dev funding) and PhysX becomes irrelevant (or more likely better optimized) in the face of AAA titles using open source physics, or Gaming Evolved turns into another stillborn
GITG
Personally, I can't find a great deal to get excited about. PhysX was bought,paid and further developed with nVidia capital investment, so I don't find it overly strange that they would protect their investment, any more than AMD would allow nVidia graphics to use AVIVO (as example).
I would also add that if it were not for nVidia's huge brand awareness and loyalty/fanboyism garnered through TWIMTBP (something AMD only lately seems to be aware of and is attempting to match/combat) and providing SDK's (inc PhysX) and funding then two things seem certain;
1. PC gaming would likely be a great deal poorer, and..
2. nVidia would likely be defunct as a desktop graphics company given AMD's advances over the last two generations of cards...and anyone want to guess the MSRP of graphics cards when a manufacturer has only Intel IGP's and S3 as competition?