Here's a proof-of-concept implementation of a i2c-based fly-by-wire throttle setup.
Its very similar to the i2c sensor network prototype, but it uses a servo for the output instead of a gauge.
The accelerator pedal is an arcade unit from happ electronics. its been in my parts bin waiting for the day I turn it into the foot control of a DIY tig welder.
here's a descriptive video on youtube: http://www.youtube.com/watch?v=tciLgdMQsOE
here are the sketches:
here's the hex: