[OM] Handwarmers/Camera warmers?

[Doggre]

Chris mentioned reusable handwarmer packets.  As well as warming hands, how 
about keeping the batteries warm in the OMs that are otherwise susceptible to 
cold?  Maybe rubber band a mini pack under the battery compartment?

http://www.rei.com/online/store/Search?stat=7889&langId=-1&storeId=8000&;
textQuery=handwarmer&x=21&y=10

Rich