This has more or less been common knowledge since GamesCom. However, a lot of people were confused or thinking it might be a mistake. Game stores have changed the release date all over the place, from October to September back to October...it's been a mess.
EuroGamer was able to get a hold of Warner Bros. and revealed that there was indeed a delay. For you Europeans, the date to mark is October 9th, a little over 3 weeks past the US date.