spolier warning for those who havent seen the hulk yet ....

k if you go out and see iron man k and wait till after the credits nick fury says that there gonna start the avengers project k 

then if you go out and see the incredible hulk at the begining you see stark industrie stuff on the titles k and then at the end tony stark comes up to the  general and starts talking (dont wanna ruin it for you)

k so now they gotta make movies for thor captain america and ant man and the wasp (those two probley in the same movie)

k cause the avengers team is made up of those and iron man and the hulk so lets go out and see these movies and get pretty excited at all the hints they start sending our way 

 i think the avengers movie is set to realese 2011

 You can also see in Iron Man that Tony Stark is making Captain America's shield on his desk in one scene, a quick google search will show it to you.