I avoid Sleet, Snow, Sand, and Salt...but on a cold, dry Indiana day without any of the 4 dreaded S 's previously mentioned, I will often exercise a Snake or two as long as I have time to get the Viper up to full operating/equilibration temp (usually about an hour's worth of driving with ambient temps in the 30's)...noting that it takes over 30 minutes of highway driving to get the OIL temp to register above the miminum mark of 180 degrees in an SRT-10 in spite of the water temp of 190's.
In my opinion, letting them sit through the winter (with proper attention to the fluids beforehand) is FAR BETTER than an occasional warmup or short drive cycle.