Quite a few eyebrows were raised when Amazon's patent for an "anticipatory package shipping" system came out earlier this year. The idea that Amazon presumed to know its customers well enough that it could begin shipping their orders even before they click "Buy" seemed almost paranormal.
In fact, all the patent was really laying out was a process by which items would begin to move to the general geographical area of the buyer in the event that he or she completes the purchase. Given Amazon's ability to analyze customer data such as purchase history, product searches, wish lists, and shopping-cart contents, it actually doesn't seem too outlandish to think it might know when a purchase is likely.
The patent does mention the possibility that a package may occasionally be delivered to a customer who never actually completed a purchase. Rather than pay the cost of returning or redirecting the package, Amazon would simply give it to the recipient as a gift "to build goodwill."