I could test the game on PS3 last week end and honnestly it seemed very decent. Actually the 2006 PS2 game was already a big improvement over the horrible 2005 version, but it was still ugly graphics.
The PS3 version is really beautifull, while keeping the decent physics of the last game. Only thing that bothered me was the triggers buttons L2 & R2 used for downshift and upshift have a long course on the new dual shock (like a x box trigger) and that was annoying at the beginning, but you get used to it in three laps.
I'm sure there will be a good steering/pedals package for PS3 soon, but I don't think it will be a formula one type.
I was also impressed by the Gran Turismo HD graphics! but the demo is really poor, with only one track (mountain type with slow hairpins) and no opponent! you can only set a time or drift. That's cheap...