In 1995, I built systems for the USAF / AFRL based on data gloves and Polhemus trackers and I was not the 1st. We used this for 3D environment interactions and had many types of gesture recognition. Reading Google's patent claims, Google positioned the sensor on the finger tip (ours was on the back of the hand) and then applied all prior art to that minor and obvious 'novelty'. This is a minor departure from prior art, but is inline with how the US patent system works: you get a patent in exchange for full disclosure, then others get the opportunity to improve upon your invention and then patent their improvements. As a technologist, I look at this as a cheap copy, but from a patent perspective, they took prior art and built in a new way. If this spawns innovation, then cool, and if not, then it doesn't matter. I predict that, if successful, Google will see a few patent challenges.