Not sure how much to believe in this story, although Cult of Mac is usually a good source.
http://www.cultofmac.com/152290/why-your-new-ipad-wont-be-delivered-before-friday/
"Because Apple has the new iPads locked up in their own private 18-wheeler trucks. These trucks are on FedEx property, and entered into FedExs system, but FedEx has been told that Apple will not unlock these trucks until Thursday evening."
http://www.cultofmac.com/152290/why-your-new-ipad-wont-be-delivered-before-friday/
"Because Apple has the new iPads locked up in their own private 18-wheeler trucks. These trucks are on FedEx property, and entered into FedExs system, but FedEx has been told that Apple will not unlock these trucks until Thursday evening."