I noticed the same thing last night on my 05 Limited Roadster. Seat moves fine, still, haven't checked the heater yet. Concerned because I noticed this after I got the rubber-glove treatment going through Canada Customs last night, coming back from the US. Idiots did a search for no reason, wouldn't let me watch as they went through the car, so I've been wondering if they did this while trying to cram their hands under the seats.

So I hope that somebody can confirm that this plug is a leftover and isn't supposed to be plugged into anything. I can't find a place where it would go, anyways. Really pissed off about this, in addition to how I was treated last night by a pack of power-hungry wannabe cops.