Over at IMDB user, elektranz has posted something great.
" Hey, i work as a projectionist for a theater complex, Berkley Cinemas, in Auckland, New Zealand and we just got an email from Paramount today to say that they will be sending out the first trailers for Iron Man 2 and Shrek Forever After next week to be played before Avatar beginning Dec. 17. :) just thought i'd pass along the good news."
Just as you, I'm not sure how much of this to believe, But I checked out the user's profile, and it seems that he doesn't have an history of false info, so who knows. I really hope this is true. Also the user says he works in New Zealand, and accroding to the official Iron Man 2 site, New Zealand gets to see the film a week before the Worldwide release on May 7th. So they may get the trailer before the U.S, while be wait for Christmas Day with Sherlcok Holmes.