Adrian's Rojak Pot has posted a (p)review on the NVIDIA SLI Physics Technology:

Well, I guess it's pretty much expected for NVIDIA to find some new way to utilize all those extra processing power in their latest GPUs. To be honest, we actually expected them to integrate audio processing into their GPUs... but SLI physics sounds like a good alternative! In fact, it sounds like a great way to offload work from the CPU to the GPU. After all, even the high-end CPUs have trouble keeping up with the latest graphics cards from both NVIDIA and ATI. This will allow the graphics cards to deliver better performance without being limited by the CPU. Of course, those are just assumptions based on limited details and a single benchmark results. We will need to see just how much performance boost we will get with a single GPU and a SLI configuration when we get hold of a driver and game that supports SLI physics.

Another preview can be found on HardOCP:

Thankfully out of all the methods we've heard about so far it seems using GPUs as dedicated physics processors will be the smartest way to gain this acceptance. The install base is already there. Havok FX can utilize a single GPU or with NVIDIA's SLI open up even new possibilities. Imagine if you will QuadSLI; two GPUs doing 3D rendering and two GPUs doing all physics. What an immense amount of processing power! It will all be up to the game content developers to show us what they can do in games with that kind of power. We need to see compelling reasons to want this technology. So far we haven't. It looks like 2006 may be the kick start, a sort of revving up on the physics side of things and by the time we hit 2007 physics may just be the next '3D.'

I prefer modular approach of AGEIA, moreover it's not limited to effects physics... I think it's way better that you can make all movements and particles affect gameplay...But most people will probably prefer it being CPU or GPU based, even if it take some performance. Rather than to buy a 250$ extra addon card with its own fan and noise....

What implications does this have for Ageia's PhysX processor? I'd much rather have a dedicated Physics card than deal with the bugs inherent in "sharing" graphics processing for use in physics calculations. It's a shame it has to be nVidia doing this because when push comes to shove it won't matter who's tech is better, nVidia's is going to be the standard.