Force feedback in games is controlled by the game, not the console. The software (the game) tells the steering wheels motor, when and what direction to spin. By ways of sending electricity to the motor. The more current to a DC motor, the more resistance it has.
Any console that can send current to the controller, can have force feedback. PS3 can send current to the PS3 controller (in this case, a USB, so it HAS to send current). That being said, why the US GT5 doesn't work with FFB doesn't make sense. But, the Japanese version is different from the US version, so, that small difference means no FFB. This could explain why FFB only works on the Japanese version of PS3.
The first japense version downloaded on u.s ps3 from the japanese store had ffb, ffb obtained through this method is not allowed to happen in the U.S so The Japenese version was updated to recognise the region of the console.
When the exact same japanese version is downloaded to an american ps3 it recognises this and doesnt allow the ffb code to work or show the menu options.
When the japenese version is played on a japanese console, it recognises this and allows the code and menu options to enable force feedback.
I.E the software has been coded to Prevent U.S users from getting forcefeedback regardless of all the efforts and methods tried by determined gamers to make use of ffb in the u.s.
This shows the length Sony are going to to ensure the dont impinge on any of immersions patents in the U.S at this time, they can not afford to give immersion any form of reason for further attack, especially at a time when Sony are once again arguing their case over the original lost case against immersion for rumble.
Any evidence that Sony was once again seemingly infringing on any of immersions patent would be viewed extremely dimly by the court and would show the judges that Sony didnt take the original court ruling in favour of immersion patents seriously.
(FFB in GT DFP wheels and any other logitech wheel is operated by immersion patented technology control chips and code which controls the the way the wheels ffb function works, to make use of the forcefeedback technology within those wheels the game has to code to immersions technology contained in them to make ffb work, Sony do not have permission to do this in the U.S from immersion due to the continued litigation, ongoing over the rumble case, the reason it is able to do so outside the U.S is less clear, though immersion hold less patents outside u.s which could be one reason, or immersion may have allowed regions outside the u.s to use it so as not to burn all bridges with sony,after all the rumble case is only against SCEA, and has only any affect on SCEI with regard to importing hardware orsoftware into the U.S territory)
The American version has never had the code enabled for forcefeedback.