It seems a recently added feature (or one I only just noticed, anyhow) but I wonder how it is supposed to be used?
I can perhaps understand it for PDF products (since you might want to wake up and download something at whatever time it comes online - I presume those files will automatically become available at the prescribed hour). However, I can't see how it will make a difference for physical products (which also seem to have an "8:00/EST" or whatever appended to the expected date.
From a customer perspective, will I see any difference if I preorder it and let it roll over automatically at the appointed time or if I log on and place an actual order on the day it becomes available?
One difference would be if they have given out a discount code. Since those discount codes usually don't apply to preorders, it might be useful to know when you can actually get the discount on an item.