Does anyone know anything about the internal workings of the accelerometers used on the N900? My interest is professional - I know quite a lot about seismometers and full-size accelerometers.

I had assumed (perhaps foolishly) that it used piezo-electric accelerometers. These and all the other small motion sensors that I know about are only capable if giving an output in response to a change in position. They give no output at all if the device is not moving and so could not be used to determine the orientation of a static device.

The wiki page demonstrates that the N900 accelerometers do vary their output with orientation and so can be used to determine orientation.

For the life of me, I can't work out how they do it.