Watch out for your non weather-sealed lenses, though.
The trick I've heard with the plastic bag is to put the camera in the bag when coming back inside, since as glasses-wearers know, that's when condensation appears. Going from warm to cold shouldn't be a problem.
The cold temperature will kill your battery life (temporarily), but I don't think will be a problem in itself. The 0C rating has got to have some safety margin built in. I don't think I'd stay out in that for hours, but I think that's true even without a camera along.
