In reply to Indy:
I used to commute by bike through the Finnish winter - down to about -15 (I got superficial frostbite in my toes riding home one day when it was colder than that so started to use the bus when it was really cold!). Despite using cycling gloves the rest of they year, for mid-winter I used windproof fleece gloves - Lowe Alpine ones with suede on the palms and two fingers - good for changing gears and braking. The key thing is not to have them tight.
I bought some lobster claw ones too and they are alright but a clumsy for changing gears on my CX.
Post edited at 21:57