Hm. Hasn't been a problem for me. The front brake is all I really need, and there's all of about 14 inches of cable there. Even if it were full of ice (which I don't know how that would happen) I think I could pull hard enough to break it loose (not that I would have left the garage with the brakes not working anyway).

I actually went with cable actuated discs because of stories of hydraulics not working in the cold; one drop of water in the system, freeze, and no brakes.

I recently saw some hydraulic rim brakes though, and that looks sweet for rears.