Rockstar has put together an advertisement for Grand Theft Auto 5 in New York City, running it as a PlayStation 3 title and somehow forgetting to mention that it’s also available on the Xbox 360.
For whatever reason, the ad only reads “September 17, on PlayStation 3” without bothering to mention that the game will also be out for Microsoft’s platform, as the game is a multi-platform release that will be out for both consoles on the same day.
Why not advertise both the PlayStation 3 and Xbox? The simple, and most uncomplicated —and likely—reason for that is because Sony and Rockstar seem to have a publicity deal. It’s also why the game has only been shown on the PS3 and why the demonstration of the game was also depicted on a PS3 with PS3 controls instead of the Xbox 360.
Given this possibility, don't be surprised to see more co-branding of the game on the PS3. It may not necessarily mean that the game was developed on the PS3 as its primary platform, but Sony certainly intends for it to seem that way.
Image source: GTA Forums