Sensor fusion implemented on Android?

Question

I listened to this talk: http://www.youtube.com/watch?v=C7JQ7Rpwn2k

which is Invensense Inc prototyping their \"Sensor fusion\" system, which is where they combine gyro,

Answer 1

There is no such thing as a 'gravity' sensor (ignoring the search for gravity waves!). Gravity IS an acceleration and hence is detected by the linear accelerometer as well as any other acceleration the sensor may be subject.