If you are waiting for Gran Turismo 5...well just ...even the damage patch for the demo sorry prologue is 6 months behind and the game has fallen off new release lists with rumours of it being canned entirely.
The ps3 wipes the xbox to the floor. GT5, has anything the xbox come up with wiped that game? in terms of driving physics and graphics? NO. And that, like you say is the prologue/long demo.
It's not my style of game but let me tell you, it's not being canned. As an avid member on the www.ps3forums.com I know my gaming stuff. Your arguing with the wrong guy about this stuff, maybe cars yes but gaming..no