I took out the new singlespeed tonight in the snow. Awesome. Epic. The bike was great. I on the other hand had a couple new experiences. My eyelids froze partially shut a couple times and my chin got really cold despite a good balaclava. I did have a head band that warmed me up nicely. It will be nice when fixedgeargus gets done with his homework so he can join in the reindeer games.
For the folks interested in the tech stuff, I was running a Ritchey Speedmax 32 on the front and a Kenda Kwick 30 on the rear each at about 40 psi. My Tektro brakes worked great even with no name old levers. Not to touchy in the snow, but just enough so I could slow down.
As far as clothes, as some of you have asked about, I use mainly Under Armour base layers and then a long sleeve jersey and a shell. Lower half is shorts, leg warmers tights and if it's snowing or raining REI bike specific rain pants. I also wore a DOT approved reflective safety vest. I might have looked dorky, but I was visible, and didn't have any close calls.
For lights I always use a Planet Bike superflash on the rear and up front I used my homebrew lights, which are about 200 lumens and last for a couple hours per battery pack.
I will try to post some more info about the light construction soon.