During Sony's Gamescom press conference, the company mentioned that pre-ordering the PS3 version of Grand Theft Auto 5 on PSN will get you 75% off any other Rockstar Games title. Shortly afterward, they provided further details for the deal.
In order to take advantage of the deal, you must pre-order the Day 1 Digital version of GTA 5 on PlayStation Network. Like the physical standard edition copy, this will get you access to the Atomic Blimp in-game vehicle; however, as an added bonus you'll also receive an exclusive PS3 theme along with the 75% off discount.
The Day 1 Digital version is available at PSN's online store or in the "New on PS3: PSN Pre-Orders" section of the PlayStation Store.