Myron B/Matt G.
You are both right, just need to make sure we are on the same page. Batteries produce electrical current via a chemical reaction process and cold temperatures do affect that process and the battery's amperage output. That's why the Cold Cracking Amps (CCA) rating on batteries is lower then the regular temperature output rating. Battery warmers can help increase battery output as they keep the battery warmer than cold ambient temps which aids the chemical reaction process so it can produce more output amps.
The speed of electrons is constant, which if I remember correctly from my college days is at the speed of light. The resistance of a material affects how much current it can conduct and the resistance varies with temperature but as Matt said, it's effect is minimal for most metals for only a 70-80 delta change in temps.
Hope that clears that up for everyone.