It's actually available now (the free content) and some people, like myself, found their USB stick woroked anyways! Pretty sweet deal to get $10 free.
Just prior to the launch of the limited edition of Splinter Cell, developers UbiSoft announced a $10 price cut. This is mainly due to a malfunctioning of a USB drive within the package. But the content of the USB drive, they say would be available for download to those who lay their hands on the faulty drive.