I doubt there is a publicly available data sheet. I think it would require some social engineering of the right people (maybe some social lubricant) to get any details on the sensors used, hence the reverse engineering required.
Can't believe patents are granted on something like this. Take two off-the-shelf sensors, hook them together a minimal of circuitry and patent "in a bin." Add "in a phone" and you can have a new patent to make money with. Astounding. Yay for fostering innovation.The combine forum thread mentioned SHT15s as well, so that's probably what you have.