Frenchie fibber/director Louis Leterrier supposedly spilled the beans straight out of a Marvel meeting with Jon Favreau, but don't get too excited. He's been known to play fast and easy with the facts...
This from Den of Geek...
Louis Leterrier says new Avenger will feature in Iron Man 2 and Jackson, Downey and Norton set for Avengers in 2011
Louis Leterrier has revealed not only that Jon Favreau is currently writing Iron Man 2 with Robert Downey Jr., but that the sequel to the Spring blockbuster will feature a new character from the Avengers, after the brief appearance by Samuel L. Jackson as Nick Fury in the post-credits sequence of Iron Man
Pretty good news, finally something new on Ironman 2 and The Avengers.