Spider-Man 3 producer Grant Curtis wrote in his official Blog that the new trailer is coming this fall. Fans speculate that could mean it'll premiere with the Nov. 17 debut of the new James Bond film Casino Royale.
"In regard to the next time you will get a glimpse of the movie, please know that we will have a trailer coming out this fall. Although I am not at liberty to say when exactly it will hit the theaters and internet at this time, I can tell you that I have seen a rough version of it and I am confident that you are going to be blown away. It is an incredible piece that showcases the full scope of the picture, both in terms of the gripping story as well as the groundbreaking visual effect shots. Be patient, it's going to be worth the wait."
You can read more here.