There are many ways to use the deep web. Both good, evil, and in between. The Google Hacking Diggity Project is all three.
In this case, a deep web tool-set was developed to aid penetration testers (white hat), hackers (black hat), and hobbyist (want a hat) to gather open source intelligence (OSInt) on potential targets to aid their hacking attempts.
The focus was to use Bing and Google to the max to dig out some kind-of-deep-web assets to the fore.