The costume pack will add new alternate outfits including a Jack Kirby-style Thor, the dastardly Norman Osborn's 'Iron Patriot' suit of Iron Man armour, Ryu in his lurid original Street Fighter outfit, Chris Redfield's S.T.A.R.S. uniform and more. It'll be released for Xbox 360 and PlayStation 3 on March 1, priced at $5 (400 Microsoft Points).
March 1 is also when the 'Shadow Mode' DLC will be released. The promised release of Jill Valentine and Shumna-Gorath as downloadable content will happen some time after then; the pair are presently available only with the Special Edition.