Probably only a mockup, but such a wonderfully weird idea that I wanted to share. From Momentum:

Iron Saddle
Who hasn’t suffered from ‘cold butt’ while riding in winter, at least in the northern parts of the continent?… A battery, a 12 volt iron (without steam option) and voila! Toasty Buns! And of course if you are truly nimble you can iron your clothes while you ride.