The report details a number of examples of tightened security for Apple's own employees, including reductions in off-campus testing of prototype devices and retail store changes such as reductions in the amount of advance access store employees have to OS X and iOS system updates.
Still, Apple's supply chain obviously represents the weakest link in the chain of product secrecy, with an assortment of vendors producing parts months ahead of a product's public launch and numerous opportunities for security to be broken along the way. Ars Technica notes that product security is an ingrained part of the culture at Apple, with employees honoring that secrecy out of respect for their coworkers' efforts.
But that sense of loyalty is largely lacking in the supply chain where companies churn out millions of parts on a contract basis with relatively little investment of loyalty. Apple naturally keeps a close eye on its supply chain and its partners are undoubtedly concerned about losing Apple's business should excessive leaks be found, but it seems to be nearly impossible for Apple and its partners to keep everything under wraps.
Article Link: Apple's Focus on Product Secrecy Thwarted by its Massive Supply Chain
