The trial winter garden has been growing quite well. My only regret is not making it larger :-)
I've been able to pull out bits as I want them from November on into the 5 degree January we've been experiencing here in Tennessee.
I did end up loosing my Paris Island Cos Lettuce, Buttercrunch Lettuce, Purple Broccoli, Swiss Chard, Wando Peas, and Bok Choy to the frost. Next winter I will try covering the garden beds with some Reemay or a similar row cover to keep the frost off. Territorial Seeds has a pretty good collection of row covers, though I don't think I'll worry about the hoops... just drape it over the plants.
Despite the extreme cold, for here anyway as we usually don't go below 20 degrees in the winter, winter harvesting is still a great deal of fun. Clockwise we have carrots, leaf cabbage, parsley, kale, Jerusalem artichokes, and turnips (the turnip greens succumbed to the frost). I had to knock the ice off of the leafy greens... hardy indeed!