I ride in winter all the time. Oh wait... I live in San Diego. What's winter?
On a serious note - I do get my dirt bike in the snow frequently, but the street bikes rarely see snow (typically only at high elevations). Do gear up - and be prepared to spend a lot of time in the elements in case something happens. Carrying a few little things like a thermal blanket, trash-bag poncho, light sticks, heat pads (the ones that you break or knead and they start heating), some food/water, etc. can really help.