By way of MacRumors comes this Reuters piece that outlines some of the steps Apple takes with regards to secrecy to closely guard its new products before they are launched. They focus on the iPad and how Apple employees have known only as much as any average Joe that reads the tech blogs and other Mac enthusiast websites.
They go on to mention that not even the in-store technicians, known as Geniuses, have any idea about new products before launch day. At best, they get their hands on new products the morning of the official launch.
Apparently Apple has even been known to send two pallets of product to their stores. One in which there is absolutely nothing, and another that has the actual product. Each is kept under close supervision so that not even a snooping employee could get a peek before the appropriate time.
The last interesting bit is that employees, who are given a 25% discount on Macs and iPods (but not the iPhone), have still not been informed as to whether or not they can buy iPads with their corporate employee discount.