Rather than guessing when GT5 is released I feel its better to try and predict the release date via a process of elimination.
So lets start looking at dates and assume GT5 will be released on a Friday in the UK as most games are. This leaves these dates Nov 26th, Dec 3rd, 10th, 17th, 24th, 31st.
So we can assume GT5 won't be released on the Dec 24th, 31st for obvious reasons so this cancels these dates. Now the 17th is unlikely due to most people have already finished their xmas shopping. So the possible dates are Nov 26th, Dec 3rd, 10th. Now personally I reckon its between Nov 26th and Dec 3rd because this is the peak period of xmas shopping.
You may wonder why I haven't included Fridays before Nov 26th but in my opinion I reckon we would of heard of a release date already.