Ended up calling a towing company, and got a great truck driver. He was able to tell me that the problem wasn't the battery, it was actually the safety switch. It must have gotten stuck, possible due to the cold. A little fiddling with the shift and he got it to start right up. Its a problem I may have chronically, or may never have again for the life of the car. In any event, he showed me to how to handle it if it does happen again, and gave my battery a shot of WD40 for good measure. So, all in all, the easiest possible resolution to the problem.