Something I am sure many game developers and the open source community will approve of. Writing about it on their official blog, NVIDIA said "We’re doing this because physics simulation — long key to immersive games and entertainment — turns out to be more important than we ever thought.".
Originally from NovodeX, which was later acquired by Ageia and then in 2008 Ageia itself was acquired by NVIDIA. Instead of focusing on a dedicated expansion card, NVIDIA decided to work with it together with their own GPUs.
You can find it on GitHub under the BSD-3 license. It's good to see NVIDIA do more like this.