Gran Tourismo 5 Prologue has been given early to some websites and it seems that there is already a patch available. Geekpulp writes:
"You can imagine my excitement after being given access to download a copy of GT5 Prologue to review. After getting myself comfortable in preparation for a few hours of solid racing, my excitement was stopped dead in it's tracks. The game downloaded pretty darn quick for 1.9BG (about 90 minutes on my weak connection), but after starting up the game I am prompted to perform a game update."