The image below debuted in the print edition of Empire, but the scan was made available by the good folks at Coming Soon.  As you can see, those members of Earth's Mightiest Heroes whose sartorial choices are made by SHIELD tent to sport elaborate boots complete with many a buckle and strap.

The costumes in the film are designed by Alexandra Byrne.  She's an Oscar winner for her work on 2007's Elizabeth: The Golden Age, though she's also been nominated for Finding Neverland, Hamlet, and Elizabeth.  She made her first comic book contribution last year with Marvel's Thor.  Tasked with updating Cap's outfit from the WWII costume of Captain America: The First Avenger, she streamlined and modernized nicely, though the helmet looks a bit goofy.

The Avengers, as written and directed by Joss Whedon, is set to hit theaters on My 4th.  Then you'll be able to see the three characters above facing off against Tom Hiddleston's Loki and whatever malevolent forces he's called down to Earth.  Robert Downey Jr., Mark Ruffalo, Chris Hemsworth, Samuel L. Jackson, and Cobie Smulders also help out to fight bad guys and make a lot of money for Marvel.