I didn't see it listed as an accessory in any of the brochures I've looked at. I think that they may be required or at least available for the ones sold in Canada. Maybe our Canadian members can answer this.
To answer tcocsr question, engine block heaters are used in colder climates so that the engine will start easier or even start (depending on how cold it gets overnight). You don't see them much around here in the Albany NY area.