The V654A ASIC die (seen on the left) converts the tiny capacitive signals from the GK10A MEMS die into a digital signal which is fed into the iPhone 4.

This data is used, for example, to turn the steering wheel of a car or to aim a gun in one of iPhone 4's many video games.

For the mechanical engineers: the sensitivity of MEMS gyroscopes is usually in mV/dps (or degrees per second), so the output of the oscillator (in mV) divided by the sensitivity (mV/dps) provides the angular rate applied to the package, in degrees per second.