The physical connecter may be a slip ring.

This place has pretty graphics of slip rings: http://www.rotarysystems-sr.com/

There are lots of few-wire protocols and something that critical probably uses several methods. My guess is that there's backup battery power in the wheel and an inductively coupled data channel (like NFC and some RFID).

Should be no more complex than a laptop dock connector which also clicks in place.

except for, you know, the part where it has to fit onto the end of the steering column between the drivers' knees, withstand strong forces without malfunctioning or becoming dangerous, and operate in all weather conditions.

An example of the forces involved on the steering wheel - Petrov's crash earlier this year where he jumped the car and the steering column broke: http://videos.larioja.com/informaciondecontenido.php?con=343...

The display alone looks like it has well over 100 discrete segments. Has to be serial something-or-other.