I agree 100% with Scooter.
( especially the part about "too cold to hold"! )
There's one thing neither of you covered...
Plastic Bottles...
IMHO: The plastic may have a slight bit more of insulatave properties due to it's density or lack there of.
Denser materials for the containers, glass or metal, will have less insulation and should conduct the heat out of the "precious" liquid stored within, be it suds or soda.
Sounds like a science project to prove this is necessary.
Anyone got two thermometers, a glass bottle and a plastic bottle, some room temperature water and a little time to test it for us?