Hey all, Happy New Year! I thought I'd post a follow-up to this thread.
I have learned that the chickens do indeed lay eggs in the winter. I was unclear at first whether production slowed or completely stopped. Our six Rhodys were pullets when we got them in August. Without any intervention on my part, we started getting eggs around Thanksgiving. Three of them are now laying, and I assume the rest may start up soon.
In early December, I decided to install in the coop a "lamp" only to provide a little bit of extra heat, and not for the light itself. The lamp I am talking about is actually a module from an old traffic signal with a red lens, illuminated with a 67-watt bulb. I have it situated in such a way that very, very little light (again, it's red light) is cast into the coop. Most of the light is shaded from the chickens. I often keep it on all day/night when the temperature is consistently below freezing, which it was for a couple weeks this past December. It probably makes little temperature difference overall, but it's at least something.