Harry Callahan "Chicago (Trees in Snow)" (1950)
A few of you have noticed issues with shooting in cold weather. Here's a tip about avoiding condensation build up when bringing your camera in from the cold:
Let your camera warm up slowly. Place it on a cool windowsill or an unheated porch for a couple of hours so it can rise slowly to room temperature. Condensation can play havoc with an all-electronic camera. This is where the suggestion of wrapping a cold camera in a plastic bag comes into play. The moisture will settle on the outside of the bag rather than on the camera's outside and inside surfaces. You can protect the delicate electronics this way. In fact, it's best if you place the bag on the camera while still outside, not when you bring the camera in.
And here's an article with a few more tips to keep your camera safe in the cold: