Ok. As someone who has both had a business that sells online and done extensive buying online, let me put my two cents in...
On day of purchase, a buyer puts cc in for the order, and company puts a PENDING charge on the account. This ensures there are funds available to satisfy the bill. This pending charge stays on the CC until time/day of shipping, at which point the transaction finalizes.
I agree that transactions should not have been FINALIZED until day of shipment (this btw could be the source of the issue pertaining to double charges IMO). As for those comparing PS to eBay, you're talking apples and oranges. eBay is an intermediary between two consumers (at least that is the original business model), PS is a company that IMO should follow standard practice that all other companies who sell online follow.
All that being said, I chalk this up to unexpected issues pertaining to initial volume of orders. Lets face it, we blind-sided them with initial sales. We could have worse problems IMO.