Although the sources on this are good and plentiful, consider any release date information on Gran Turismo 5 to be nothing but a rumor until you have the game in your hand, slide it into your PS3, and take a few laps. Even then you should probably look at the game with a hint of skepticism and worry that the disc might suddenly hop out, jump back in its packaging and fly back to Japan were a series of very apologetic game developers explain that it will be out soon.
The website Gamer Blorge is claiming that retailers have already received copies of GT5, and the release date is likely going to be November 30. And they are not alone. Reports are flooding in from Australia and several parts of Europe, claiming that the game has arrived, even though Sony has yet to officially announce a release date.
At this point it is hard to know what to believe. November 30 does seem like a possible release date which would give GT5 plenty of time to advertise, but Sony and Polyphony Digital have so badly bungled the development and release of the game that was originally announced for 2006, that even if it is true, people might not believe it until they see it in stores.
Oh, and the website VG247 is reporting that work on Gran Turismo 6 has already begun. Although no date has been announced yet, you can likely expect it in 2014. Maybe 2015.