This is my first winter commuting. First morning of snow/ice here in Denver was on my MTB at 0530 am... front wheel hit ice as I was making a right turn. Bike went left, I superman-ed straight off. Glad I was wearing a helmet as I definitely would have cracked my yolk! Otherwise injury free except for sprained thumb. That day my boyfriend put on his used studded tires from last winter, even though the studs were worn a bit it made a huge difference. Since that day I have ridden in over 3 inches of snow to work and have not swerved or slipped at all and ice several days.
A bit of good advice he gave me was to under-inflate the tires to increase traction. Makes it a harder commute but its better than breakin' stuff.
Riding in the snow is fun, even more fun to see the wimps reactions as you ride by.