DailyTech also has managed to uncover news regarding NVIDIA's upcoming Quantum Physics Engine. Slated to be released alongside the G80 GPU, NVIDIA will be announcing a new dedicated layer on the GPU which will be reserved for physics processing and be referenced as the "Quantum Physics Engine". Essentially, this new engine will allocate spare shaders towards physics processing. Obviously, the engine will scale well with SLI as there is a much larger pool of shaders though documents suggest that NVIDIA's physics processing can be done while using a single card as well. Given the history NVIDIA has in working with Havoc, it should be interesting to see the full speed and capabilities of this solution once it is made public.
There's a thread in our forum on the topic right now if you'd like to air it out a bit on the topic.