I am going to follow this topic because I am also interested in what people are wearing.

My take is that I wont wear anything that does not breathe, even in winter. What I have done up till now is just wear layers, with a windstopper top layer. Specifically, I wear this as a top layer
http://www.goreapparel.com/GORE-BIKE...artype-jerseys

With some decent layers it is good enough for me up to the freezing point as long as there is no heavy rain.

EDIT: I completely agree with carpediem that once it gets really cold, the midsection of the body is not really the problem. With some layers I have always found it easy to stay warm. The things that get cold to the point of numbness and pain, and that are harder (in my opinion) to keep comfortably warm are the toes, fingers and ears and face (in that order, for me). There is another topic floating around about winter gear that you may want to check out. Generally, good gloves, shoe covers and something to cover my ears are important.