At the world premiere of "Captain America" in L.A. on Tuesday night, there was a partial assembly of the future stars of next year's "The Avengers." Cap himself, Chris Evans, was joined by Robert Downey Jr. (Iron Man), Chris Hemsworth (Thor) and Samuel L. Jackson (Nick Fury), plus such A-list guests as Zoe Saldana ("Avatar") and Vanessa Hudgens ("Sucker Punch").