Blech, how do you people ride without fenders? You know that's not just pure rain water flinging off the front tire up into your mouth right?
I have yet to have the opportunity to commute in snow (rather rare in San Jose) but I will ride in anything. I ride my motorcycle in snow and ice (incl. the Alps.) As has been said, there is no cold/bad weather, only cold/bad gear.
"When the rain comes, they run and hide their heads...."