They are shuffled into buckets in a way that appears random, especially if the item names are not similar to each other. However they're not truly random because the same combination of item names and buckets always results in them being in the same sequence.
Well, from the perspective of the scripter, they are random. You should not depend on items in hash tables being stored in any particular order. As this same topic has been discussed so many times, I will be adding a note to the help file.
Thanks for your comments everyone.